This is a solution for anyone who wants to efficiently store a set of gridfinity refined plates (with bins). 

I found myself with 4 sets of bins for various projects, each of which was on a 4x4 Gridfinity Refined (GR) baseplate. When looking for efficient storage solutions, I found many great boxes and drawers - but they used more plastic than I wanted to, and I wasn't looking to put the bins away, or transport them - only free up some space on the workbench, and have somewhere to put sets of bins between projects. 

So - this stacking system was born - which tries to use a pretty minimal amount of plastic, doesn't need supports to print, and works for any size of plate (2-5 provided). It builds on my previous model for a mounting system on top of a mini server rack - and just stacks a set of these to hold plates at a separation of 35 mm (or multiples thereof). 

The design uses 3 components - each of which you'll need 4 copies of. 

Frame edges - hold the GR baseplate - print out 4, and they'll fit together to make a square (or rectangular) frame. You can mix different lengths if you need 2x4 or 3x5 etc. I do get a print warning when I print these without supports by the way (see screenshot) - but it's right on the edge of what works - and so I ignore those warnings and have printed many without an issue - but that will be printer and setup dependent of course. Adding supports when printing the frame parts shouldn't add much material if you choose to do this. 

Brackets - Need 4 per layer to hold the frames together. 

Uprights - Need 4 - one for each corner. To keep these support-free, and just one part, I've needed to have a design where these uprights rotate 90 degrees on each corner - which works fine mechanically - but isn't ideal in terms of asthetics, and means that you can't (for example) fix this to a back-board without drilling (or designing) extra holes. It was a trade-off - if this is an issue, please add to comments, or feel free to remix!

All models should be in the correct orientation for printing (without supports) -but do just double-check.. 

I haven't provided different stacking height options (at this juncture) - but I did add some fixings to the top and bottom of the uprights - so you can stack-em-high if you want to. The bottom layer is spaced so you can slide one frame under it - the top layer is almost at the top of the uprights - so when you stack them, this should work out nicely for spacing. 

As ever - kudos to Zack F for gridfinity, and @grizzle17 for the gridfinity refined variant.. 

Build guidance: 

I'd suggest having at least 2 layers for stability. 

All fixings are designed to use M3 x 16 counter-sunk bolts. 

Build the layers first. The brackets have a bevelled corner running vertically along the inside of the frame (see photo)- which makes it easier to get the orientation right when building. Assemble everything loosely - then rotate the bracket to the correct orientation - and aligned to the outside of the frame - and then tighten. Repeat for each corner. 

The uprights have a groove for the layers to fit into. I've kept this a fairly tight fit, as it improves the stability when built - push the frame into this slot, and then fix with an M3x16 bolt. If you are fitting multiple layers - do this for all layers at each corner - if you try to assemble one layer at a time - you may find that you don't have the flex in the uprights to get the last layer in (a compromise when I added the stacking fixings). 

Sub-component stuff: 

This is a set of M3 bolts that includes 40x M3x16 https://amzn.to/4pyUlk9. I found this much more efficient than trying to just buy sets of M3x16 in isolation. 

These are the magnets I use for all my gridfinity stuff: https://amzn.to/3DFTKtO.  

(Note: These are associate links, which means that they don't cost you any more, but I get a small cut if you purchase via these links. This isn't a big money-spinner, but I find it so useful to have sub-components linked in models that I download - so I know I'm getting exactly the right bits without much research, and it helps support my tinkering!).