This is a stackable holder for 2.5" hard disks. I made this as a personal NAS project, so please take this as a simple skeleton.
For now there's only a OrangePi One holder accessory. Soon as I can I will release a Raspberry PI holder and various accessories like usb hub holder, voltage regulator holder and so on. Final goal is to make a complete NAS cube, with all necessaries elements (display, power module, buttons, ...). More to come, check this thing often.

No particular advise for printing, just print the orangepi holder with rotation of 90 degrees along Y axis with no support material.

I made this project to be simpliest as possible to mount, no screws are necessary, no tools, just melt plastic pins with your solder iron tip or use some drops of glue. Done!