Version française disponible ici : https://ouiaremakers.com/posts/tutoriel-diy-fabriquez-votre-propre-lightbox

In this Instructable I will tell you how to make a lightbox, a piece that will literally illuminate your room. This is a weekend project with no specific skills needed in welding or electronics.

My lightbox dimensions are 33 x 25,5 x 7 cm, but you will find all the information needed to make one the size you want it ;).

Step 1: Step 1 : Material

For this project you will need :

Wood (I used pallets)
2 mm Plexiglas
3 mm MDF
Aluminum foil
A LED strip (2 meters)
Wood glue
Nails and screws
Letters for Lightbox

Step 2: Design the Lightbox

To define the lightbox dimensions, I based my calculation on the size of the letters I bought off Amazon. Those dimensions are 6,5 x 3,5 cm and I'm willing to do 3 lines of 8 letter, taking into account the thickness of the wood all around and the thickness of the support, I got my final dimensions (33 x 25,5 cm).

I joined the Sketch Up file for those who are interested in the build, all dimensions mentioned later will be based on that file.

Lightbox.skp
Download

Step 3: Gathering Wood

Firstly, take apart a pallet and keep 3 slats, the width of the planks has to be a bit larger than final width. You will need at least two 30-cm-long and two 25,5-cm-long planks, I took a pallet that had slats a bit wider than 7 cm. You will also need another plank to make the sticks in the middle that will hold the letters (30 cm long as well).

Step 4: Reshaping and Grooving Wood

Once you got your wood, take off the part where the nails were, you can now resize them to the final dimension :

Thickness (Optional) : I started by planing all the planks to 1,5 cm, this way I'm sure I'll have the same thickness and because it makes me save time on sanding later :). This step is optional, you can skip it and still get a good result.
Width : Using a table saw, cut your planks to the final thickness of the box (7 cm for me). Then cut a groove 5 mm in depth and 1 cm from the edge, this groove will be used to hold the Plexiglas. Cut also two strips of 1 cm to make the letter-holding sticks.
Length : You can now cut the planks and the two strips to their final length 25,5 and 30 cm

Finish by sanding the wood until it is smooth to the touch. For that step I used an orbital sander with grit from 80 to 180.

Step 5: Cutting the Plexiglas

The plexiglas used is opal, this means that it is white but you can also see light through it. If you wanna be sure you have the right one, place your hand behind the Plexiglas and if you can see it that's the one.

Now cut the Plexiglas to get a piece of 23,5 x 31 cm. If, like i did, you use a table saw to cut it, don't forget to put masking tape on the line where the blade will cut, this will prevent tears out. The cut can also be done with a skill saw if you are more comfortable with this tool.

Then make a test fit with your piece, make sure it fits well in the groove and if not cut again until it does.

Step 6: Cutting the MDF

This step is the same as the previous one, this time the MDF has to be 25,5 x 33 cm. I used the skill saw for the MDF because the sheet was to large to manipulate over the table saw.

Step 7: Cover the Inside of the Box

In order to diffuse the light evenly inside the box, it is necessary to cover the inside of the box with aluminum. White paint works too, but I didn't have any and I had a roll of aluminum foil.

Apply a thin coat of glue on the parts to be covered (planks and MDF) and then put the aluminum foil. Don't be an idiot like me and keep a space clear on the small planks where they will be linked to the long ones. I had to sand it again to remove both aluminum and glue on those areas.

Once it is glued put something heavy on it while the glue is drying to make sure the foil stick to the wood.

Step 8: Assemble the Frame

Slide the Plexiglas into the groove, take the protective film off around the edges (to avoid it getting stuck in the groove) and put together the frame with wood glue and nails. I used a nail gun but a hammer works fine too.

Then place the two wood stick to their final location and trace with a sharpie on the protective film where the screws will be. I found handy to use two wedges a bit longer than 6,5 cm (the size of the letters) as seen on picture 6. Then drill holes for the screws in the Plexiglas to avoid shattering it later, I used a 4 mm drill for 3mm screws.

You can now take the whole protective film off and screw the to holding wood sticks. To maintain the ticks while screwing you can use masking tape ;)

Step 9: Setting the LED Strip

Remove the protective strip to expose the sticky part and apply the LED strip starting on the and where the USB plug is. Install it around the frame and keeping it the farthest from the Plexiglas to have the best light diffusion.

Step 10: Fixing the MDF

Before fixing the MDF on the back of the box, trace and cut a hole for the USB plug, the cleanest result I obtained was by using an utility knife for that (not seen on the pictures).

Finally you can fix the back of your box with screws, that way you can take it off later if there's any problem.