I bought a set of inexpensive bamboo trays from IKEA intending to use them for eating on the couch… but I found that they're also really useful for taking projects with me as I move around my space.

I can put everything I need for, e.g., a sewing project on a tray, and carry the whole thing around with me if I decide I want to move from the dining table to the couch. Then I can put all of my Allen wrenches, drill bits, digital calipers, filament cutters, etc on another tray and keep it next to the 3D printer, and it's easy to move everything out of the way in one go. The only problem I have is that I need to find free space on another flat surface, and with my ADHD, that… isn't always easy.

Then I watched Alexandre Chappel's video about making “the Ultimate Assortment Cabinet”.  I absolutely don't have the tools to build that, or the space to keep it… but it did inspire me to order more trays and make it possible to stack them neatly.

Design notes:  the tray has an internal height of ½" from the surface to the top of the walls, so I made these stacking clips with a ½" standoff to allow at least an inch of space between trays.  (It's actually a little bit more than an inch because there's a gap at the bottom that I didn't bother to measure.)

I've copied the design into a fresh .f3d file with all the parameters in there in case you'd like to tweak it to your own preferences, but if that doesn't work for you (taller, shorter, looser, tighter, etc), feel free to comment.  I'm still pretty new to Fusion 360, but it's easy enough for me to tweak most of the parameters and export a modified STL.

Printing notes:  These are designed to print neatly on their side.  There's an 0.1mm tolerance on both sides of the clip; this works fairly well with my MINI+.  I'm impatient, so I used a 0.25mm layer height in PLA with 20% infill and it looks fine to me.  I suggest at least six per tray (one each on the short sides, two each on the long sides).  There should be minimal post-processing:  there's a 1mm fillet on all the surfaces you're likely to touch, but depending on your printer, you might need to file or shave off the “elephant foot” on the side.

[Note:  I printed quite a few prototypes, but as of this writing, I haven't made a batch of the final version yet.  Will update with photos once I have some!]