This is based on a number of existing racking systems found here. In particular thing:4125055 and 4078710 by russross. However all parts are freshly designed in Fusion 360.

My objective was to have something to support a few Pi 3B+ and Pi 4B machines. Pi 4s usually needs cooling so fans needed consideration. My Pi 4 machines have SSD cards connected so are taller and I have one with a PiJuice UPS as well making it taller still.

So, I set off to create a flexible system adjustable by others to meet their needs. As yet I have not made it 19 inches long so have not created the wings that this would necessitate. One day I may buy a frame and an ethernet switch supporting POE - but not yet.

I stand mine upright at this stage. So there are feet sized connectors to facilitate.

I used a length of 3/16th inch threaded rod from my local Bunnings and cut it into lots of 18mm lengths. Apologies for the mixing of imperial and metric. I am a metric person but bought what I found in the shop !!

I have uploaded .STEP files to enable others to edit to meet their needs. The pillar heights are the most obvious candidate.

Prusa

I3 MK3S

No

Yes

20

10 - 15%

Only need supports for the fan plate.
Print fan plate either vertical or horizontal.

Ensure that threaded rod pieces pass freely through the tray holes. They need to self-thread into the pillars.

To assemble simply screw the rod pieces into each of four feet, perhaps holding the rod in pliers to do this. Push the rods through the tray. Next screw another four threaded rods into one end of four pillars of your chosen height and then screw their other ends onto the exposed rod ends of the assembly, Repeat as many times as required. If you have a tall Pi 4 that needs an external fan then use the 18mm pillars and slide a fan plate between two of the pillars. NB on the opposite side of the frame to the power sockets etc !

Obviously, If your rod is a different diameter just adjust the pillar holes to suit.

Mount the Pi onto the cart using suitable bolts and nuts, eg M2.5 x 10mm or self tapping screws. If bolting then countersunk bolt heads will fit flush to the bottom most easily, but I found that hex head bolts will also pull into the plastic and work fine.

The hole in the fan plate is 30mm x 30mm and should be a press fit for fans of that size.