3 heads available:
Landing Gear
GA style Flap selector
Locking head style thingy (master weapon switch or similar)

fits 12mm toggle switches.
shaft head should be ~6mm and shaft length about 15mm.
these are the common found in ebay/AliExpress/etc.

Use hot glue to fix these to the toggle switch (beware of spills into the toggle mechanism)
as shaft is different sized on different brands of switches.

Doesn't Matter

No

0.16+

10%+

Master Arm head is best printed with brim (to improve adhesion ).
Flap handle head is best printed free standing on the base