Indexed Parametric Thumbwheel

I wanted new bed levelling thumbwheels for my Anet A8, but I wanted them to have grooves in the top side, so it's easier to give them a quarter-turn tweak. This is my simple-minded first go at openscad to do this.The .stl file is for an 25mm M3 thumbwheel, 5mm thick. Obviously with openscad, you can change that.

UPDATE: Having actually gotten around to fitting these, they are too big and collide with the frame. I will upload a 20mm 3mm thick one, once I've verified it works, but you can chang