This is holder for a Neopixel ring with 16 RGB LEDs (45 mm outer diameter). it's intended ro be placed on top of the D1 mini or any shield. You can then glue the ring on top of them with hot glue or double stick tape.

there are holes for VCC, GND and Data IN ports on the ring (the fourth hole is to make the thing symmetrical and easier to mount and use). There is no hole for Data OUT due to its awkward placement. It can be solved but I don't expect many people would chain something after the ring, so I ignored it.

RepRap

Prusa i3 MK2

No

No

0,2 mm

10% rectilinear

Prints easily without any raft or supports.