Needed a tray for my aircraft spark plugs, when doing maintenance. Decided to make it small enough to fit in my toolbox, stable enough not to tilt - and orange, so it can be easily found,

19 mm dia and 20 mm deep holes to fit REM/RHM.

Edit:
On popular request I created a 6 cyl version too. I haven't printed this one, but I will as soon as I have that Zlin 50L in my hangar.:-)

Sizes:
4 cyl: L130 x W70 x 25 mm
6 cyl: L190 x W70 x 25 mm