I needed a shelf for a network equipment rack and decided to try and make it on the laser. I think it came out pretty well. Shelf dimensions are approximately 17"x9". I've called this a 1.3U shelf since it uses 4 rack mounting holes, but it's probably more like 1.6U once you include the bracing on the bottom of the shelf.

The shelf is designed to be made out of 1/8" (~3mm) material, and fits on a single 12"x24" sheet. I've put letters on the various tabs and their corresponding slots; between those and the pictures, assembly should hopefully be relatively easy to figure out. I chose to assemble the base and the side braces separately, then put those pieces together into the final shelf. I would recommend using as many clamps as possible and putting square blocks in the corners to support the shelf while the glue dries. Even with all that, I didn't manage to get the shelf completely square; your mileage may vary.

The strength of the shelf will obviously depend on your materials, glue, assembly, and environment. I had a stack of 6 or 8 old hard drives on it for a while and it seemed to hold up just fine, but of course I can't make any guarantees about how well it will hold up for you. I would suggest testing it for a few weeks with some expendable weights before placing anything valuable on it. Use this design at your own risk.

I've already spent way more time on this than I would have liked, so I probably won't be updating it in the near future, but there are a few potential improvements that I have noticed, if I or anyone else was so inclined:

• I've seen the front of the shelf flex more than I would have liked when it was heavily loaded. I think another support brace near the front edge of the shelf would improve this.
• The support bracing for the shelf is currently cut out separately from the shelf. If one was so inclined, I think the support braces could be redesigned to be cut out of the slots in the shelf, reducing waste.
• The shelf is currently only held together with glue. If t-slots were added, screws could be used to augment the glue and the strength of the shelf would be improved, plus clamping would be less necessary during assembly.
• It would be possible to make a 1U version of this design fairly easily if someone needed it.