Taken From diyphotography.net
For anyone interested, here is the full step by step build of the softbox:
For the frame of the softbox I used 18mm x 10mm soft pine wood strips (90c / meter) and 20 gauge steel fencing wire. I joined the wood using a mixture of flat and 90 degree L brackets and I fastened the wire to the wood with picture hangers. For the skin of the softbox I used thin card and aluminium foil and fastened it together with aluminum tape, duct tape and staples. The front diffuser was made from white cotton fabric fastened with Velcro tabs.
The first thing to do was to build the front frame from the wood strips. I laid them out in the rough size I wanted and then measured the length and width. From this I decided to make the front of the softbox 100cm x 60cm. This should be a good size for portraits and more than adequate for still life setups. With the size decided, I marked out two lengths of 1m and two of 60cm on the wood strips.
To cut the wood, I clamped each length to the end of my work table and used my super sharp rust free saw. Because the wood is so soft it would pay to use a saw with smaller teeth (and less rust) but as this is all I had, I had to make do. To try and avoid chewing up the wood completely, I made the last few cuts very gently.
With the front frame pieces cut to size, it was time to join them together.
To make the joins I used small L brackets. This alleviated the requirement of having any woodworking skills and if there are any carpenters reading this, I apologise now for my total lack of respect for your craft! :)
Again, because the wood is so soft, it is a good idea to drill a small pilot hole for the screws to stop the screw just splitting the wood in two. This is particularly true with the screw nearest the end of the strip.
Once the holes have been marked and drilled, just add four screws for a surprisingly strong joint.
Repeat this for all four corners.
The next task is to work out how far the flash needs to be from the front panel to give a reasonably even coverage over the diffuser. Now I can’t say there is any scientific reasoning behind my technique for doing this, it just seemed to make sense to me. First I tied two lengths of ribbon across the diagonal corners of the frame. This let me see the dead center of the frame easily.
Next I mounted the frame on a light stand using a super clamp and placed it flat against the wall. Directly behind it, I placed my small flash on another light stand pointing at the fame and lined up with the center point. The flash was set to full power and maximum spread. I then stopped down the aperture on my camera and took a picture with the camera in line with the center of the frame and the flash. Looking at the picture revealed that I had the flash too close to the frame and was getting a hot spot. I kept adjusting the position of the flash until I was getting a reasonably even spread of light across the whole frame. This turned out to be at about 50cm.
With the position of the flash determined, I needed to build a frame to hold the flash in place at the back of the softbox. I wanted the flash to be mounted securely enough that it would not be able to drop out but still be easily accessible and easy to pop in and out. I decided to go with a cradle design and marked out a few small sections of wood to build this.
I cut the lengths of wood in the same way as I did for the front frame.
To join the sections together I used inside L brackets. There was no real measuring out for this; I just built the cradle a section at a time, holding the flash in place as I added each piece.
This is the finished cradle.
Here is the flash sitting in the cradle. It is actually very secure with no wobble but still slips in and out easily.
Here is the view from the other side. As you can see, all the controls are still easily accessible.
With the cradle complete, I now needed to attach it to the front frame. For this I used 20 gauge fencing wire. This is strong, light but still easy to bend and manipulate. I cut four 1m lengths and roughly straightened them out.
To make it easier to join the front to the back, I made a temporary stand for the cradle. This was just two 50cm lengths of wood joined with inner L brackets.
I used soft steel picture frame hangers to hold the wire in place. First I bent a 90 degree angle a couple of inches from the end of one wire using a pair of pliers.
I fed the end through the hole in the picture hanger and then screwed this onto the front frame (after drilling pilot holes) and then bent the remaining wire back towards the flash carrier.
I repeated this for all four corners.
I attached the other ends of the wires to the carrier in the same fashion.
Finally, I trimmed the excess wire off each end with a pair of wire cutters and removed the temporary support. Don’t worry if it all seems a bit wobbly at this point, the next step is too add a strengthening brace that will also act as the mounting point for the whole softbox.
The brace is a single length of wood with the ends cut at roughly the angle of the joint. To do this, I cut a length of wood that was a few inches too long and then with the softbox placed face down held it in place and drew the join angle onto the edge of the wood. I then sawed the ends off at this angle. To join the brace to the front face and carrier I held inner L brackets in two pairs of pliers and bent them to a matching angle. I then screwed the brace in place after drilling pilot holes.
Here you can see a close up of the join between the brace and the flash carrier.
With the brace in place, I clamped the whole frame to the table, inserted the flash and gave it a test fire. So far, all looked good! :)
The next task was to add a support onto the brace for the mounting bolt that goes into the lightstand. I used a slightly thicker piece of scrap wood for this and drew a line on it that would be parallel to the floor when mounted on the brace. I then sawed along this line.
Holding the softbox by the brace, I felt for the approximate balance point and attached the mount with screws.
This completes the skeleton for the softbox. The next task is to add the skin.
I used thin brown card (or thick brown paper depending on how you want to look at it) for the covering. First I numbered each side of the softbox and marked the numbers on the wood using a permanent marker. Next I lay the softbox on its side on top of the card.
I traced round the outline of the softbox with a marker and then expanded this line by a couple of inces.
Here is the outline of one of the long sides.
I cut out the shape with scissors and marked the panel with the side number (1 in this case).
I repeated this step for all four sides.
Each of these panels now needs to be covered in aluminium foil. Having learnt my lesson from previous projects, I splashed out a little extra and got the good stuff. Extra heavy duty turkey foil! :) I cut pieces of foil large enough to cover all the panels.
I attached the foil using a spray contact adhesive. First spray the glue on the card being particularly careful to spray right up to the edge. Next lay the foil, shiny side up, on the card and rub all over with a cloth. This smooths out most of the wrinkles and makes sure the aluminium and card are well glued. Finally, trim off the excess foil with a pair of scissors. Repeat this for all four panels.
Now we need to attach the panel to the frame. I clamped the frame to the table with the edge of the panel clamped under the long edge of the frame.
Next I cut a small length of aluminium tape just long enough to cover the short end of the panel where it connects to the flash carrier.
Lifting the panel up so that it is flush to the wires I used the aluminium tape to hold the panel in place by sticking it across the top end of the two wires and the flash carrier.
I then cut a notch in the bottom end of the panel and folded the resultant flap up and used a staple gun to hold it in place.
I cut two more small lengths of aluminium tape to fasten the bottom end of the panel.
Here you can see the aluminium tape stuck in place over the picture hanger. This should be repeated on the other side.
The next step is to cut two lengths of aluminium tape to the same length as the wires. We also need to cut off one corner to match the join angle at the bottom of the panel.
I have run the tape over the top of the wires to hold the panel in place and then smoothed it down with a cloth.
Finally, I have trimmed off the excess overlap with scissors, leaving a one inch flap which I have bent up around the wires.
The last step in securing the panel is to add a row of staples (using a staple gun) along the outside edge of the front frame.
Repeat this process for the panel on the other side.
Here you can see a close up of how I trimmed the panel around the flash carrier.
Now we want to add the panel on the side without the brace.
Start by stapling the edge to the front of the frame.
Next clamp the softbox to the table with the panel at the bottom.
Use aluminum tape to fasten the panel to the flaps of the other two panels. Here I have taped the left side and I’m about to do the right side.
With the inside taped down, trim off any excess card on the outside. Leave about an inch flap all round.
I used duct tape on the outside to fasten the panels down.
Before adding the final panel I needed to insert the bolt into the support for the lightstand mount.
After drilling a small pilot hole I worked up in drill bit size until I had a hole big enough for the bolt to fit securely.
At this point, I realised I had picked a bolt that did not have threads all the way up to the head (durr)! Not having a similar sized bolt that did, I had to use a whole pile of washers to get the nut to secure the whole assembly (so much for saving weight). The two nuts further down are to give the screw in the lightstand something solid to clamp onto.
Before going any further, I placed the whole setup in a lightstand (along with flash) to check on balance and stability. The balance was good but the support brace was a bit wobbly.
I added some additional bracing in the form of two inner L brackets and a bolt to the top of the brace. This worked a treat and really stabilised things up.
I just had to add the final panel now. As the brace was in the way, I had to trim the panel down to size before fitting it. I also needed to cut a couple of notches in the top and bottom to fit the panel round the brace joints.
Here you can see a close up of the top notch.
With the panel in place, I added a row of staple along the edge of the front frame. You might notice I have a different staple gun here. A handy tool tip when buying staple guns ... don’t buy cheap plastic ones, they are a false economy and break after five minutes use (ok, it did say it was for light duty and I was stapling card to wood, but hey I am just saying).
Again, tape up the inside flaps with aluminium tape.
And the outside flaps with duct tape.
Finally, trim up any gaps on the inside with aluminum tape. Also run a length of aluminum tape along each of the front edges folding it back on the inside and out.
Here is a close up of the trimmed up flash opening.
This is the trimmed up front frame.
The final stage is to add the diffuser panel. I used a piece of white cotton fabric for this. Laying the softbox face down on the fabric, I traced around the outer edge and then added a couple of inches.
I then cut out the panel with scissors.
I was initially going to fasten the panel with staples to the front frame but decided to use Velcro instead. This will have a number of advantages at a later date. I can remove the diffuser and add a second diffuser panel inside the softbox if I want. I can also make a diffuser with an attached grid if necessary. Finally, I can still access the inside of the softbox if I need to repair any sagging foil or other unforseen problems.
I only had enough sticky backed Velcro to use small patches, but in the end this proved to work fine and adding Velcro to the full length of each side would probably not work as well.
Before adding the Velcro, I cut a slit in each of the four corners of the fabric to make a fold when it was stuck in place.
To add the Velcro, I stuck the fluffy side to the fabric and placed the hard side on top of this. I added three tabs on the short sides and five tabs on the long sides. I also made sure the tabs on each end were not too close to the corners.
To get the hard side in the correct spot, I just folded the fabric into place so that the hard side stuck to the cardboard.
Finally, because the Velcro did not stick to the fabric too well, I popped a couple of staples into each fluffy tab to keep them in place.
I also added a tab to each corner and again held them in place with a staple.
Here you can see the flaps all folded into place and secured by the Velcro.
And that’s it, one large DIY softbox for a small strobe.
Here it is from the back. You can see a bit of light leaking out of the flash hole as I forgot to push the flap all the way down.