This grip is patterned after the Sig MCX grip. 

Inserts are separated to allow for printing in different colors or even different materials - I've used PLA, TPU, PETG, wood PLA, and others for the insert. 

I recommend printing the grip with the top flat on the plate, I didn't use any supports, use what you need. Inserts can be printed flat, but I prefer the quality with them angled (as they are oriented when loaded) and supported. 

Inserts press into place and then use epoxy to lock them in.