I printed out the Raspberry Pi Blade Center found on thingiverse on my Ultimaker 2. This was a relatively easy set of units to print, with a majority of the time needed on it to be spent cleaning up the large number of pi holders. I assembled these with threaded rods and lock nuts. The threaded rods had to be cut to size but in the end, everything was assembled in about a weekend after printing was done. In order to fit RPI 3B+ with the POE hat, I did end up hand modifying some trays, which I don’t have a model for the changes so they can be printed in that form.
In the end, I didn’t use the wiring clips that are modeled into the blade center since all I am running in it right now are POE powered PIs, the rest of my lab PIs being elsewhere. In the end I printed the primary components out of PLA while some of the trays are ABS since I wanted a few different colors for those as a way to determine which Pis are for what services. Currently the Pis are running a IPv6 tunnel and some docker service experiments.