You should know that a light box that can be used for a bunch of creative stuff, so let's get started!
The video helps to understand the whole process. :)
Step 1: Make the Box // Cutting All Pieces to Size
We start by cutting the wood to the desired size you want the box to be. This box has 60 x 40 x 8 cm (aprox 15" by 23" by 3" tall) and you can make it any size you want but I recommend not making it too shallow so you can get a better light refraction inside the box.
For the material I am using 10mm plywood that is going to be joined with 45º miters with internal splines for reinforcement but you can use solid wood or 1/2" or 3/4" plywood that you might have laying around.
To make the 45º angle cuts, I used a table saw sled made specially for this type of cuts and you can see how I made it right here.
After cutting all the 4 sides to their final size, you will want to create two rabbets all around. One is for the backer board to seat properly later and the other one is for the white opaline acrylic sheet (translucent) slide in and out if someday you need to replace it. I used 3 mm (1/8") opaline acrylic sheet.
One of the sides is a bit narrower than the other three. That will allow the acrylic sheet to slide in and out in the future. I mistaken this part when making this light box and I fixed it all up in the video so you might want to check it out first!
Step 2: Reinforce the Miters and Glue Up
Since we are using tall miters, it's quite important to reinforce them and there are several ways to do so. The one I chose and found out to be very efficient and easy to make is with hidden long splines.
It's so quick and easy once you put a stop block on the 45º table saw sled that makes the process a real pleasure.
After all the slots are cut, we need to make some solid wood splines from a strip and tune them up just so they become just a little bit lose in the slots to allow some space for the glue.
We can now glue the 4 sides with the hidden splines and a picture frame clamp really helps. Make sure everything is square and that the acrylic sheet seats nicely in its rabbet.
Step 3: Make a Top Frame to Close the Slot
Now you need to create a barrier so that the acrylic sheet stays trapped inside the groove.
You can easily do that by making a border frame with solid wood strips after cutting some miters so they look nice since this is going to be pretty visible.
Don't forget that one piece of the border needs to be thicker to match the final height of the light box (remember on Step 1 when I talked about my mistake on the video?). That is the piece that won't be glued and be able to come out if you need to remove or replace the acrylic sheet.
Before gluing up, it's a good idea to cover the edges of the acrylic with some plastic wrap so that the glue squeeze out doesn't fill the groove and also don't stick to the sheet. Be patient when removing the sheet with the plastic wrap. It will come out nicely if you take some time.
Step 4: Apply Finish and Reflective Material
It's time to give it a light sanding to prepare the box for finish. I used wood sealant and spray lacquer but you can apply your favorite protective finish.
Once the outside is done, we need to concentrate on the inside and make it as reflective as we can. A really good choice is to stick aluminium tape to the interior of the sides and also (very important) to the backer board (I'm just using a piece of thin MDF).
Step 5: LED's and Closing the Box
We are getting closer and closer to the end!
Now we just need to stick some LED strip to the sides the farest possible to the front acrylic sheet so that the light can spread more evenly and close the box. The closer the LED strip is to the acrylic, the more evident the bright line will be. And if you stick it to the backer board, you will also get bright light stripes, which, in this case, I don't find particularly good for the purpose. Unless you apply lots and lots of strip covering the entire backer board, you will always get those visual bright lines when you look front to the light box. That's why I found that applying them on the sides ends up getting a better result. But if your box is very very big, you will eventually need lots of strip so minimize the middle darker area or perhaps using an ultra bright and powerfull LED strip might work.
After closing the box and attaching some wooden holders on the bottom, you will need to drill a few holes to insert screws from the front on the movable border piece.
Now you just need to plug it on and make cool stuff with it!
Step 6: More Projects!
If you enjoyed this project, you should check out more videos on my channel and don't forget to subscribe!