Blinkytape Controller is a 10mmX26mm NeoPixel controller. Blinkytape provide the heatshrink  tubing version for it which is with the JST connector version. 

But if you want to build a little fancy case with cable strain relief for the controller.  Also want to make the case as small as possible.  I draw a case with snap hook edge.

Printer is Prusa MK3

Print with support material and 0.15mm/quality setting