I've been useing a cut/shaped piece of compact foam(like on bumper of 1/10 tc) then stick with d/sided tape. works 100% unreal. A Hitec Agressor i bought yrs ago had one in with the radio as an accessory, it ellimilnates the gap perfectly. I tried fuel tube , other tube, heating/breaking coz it went brittle then having to plastic weld a piece on for break/lever haha! haven't looked back since useing the dense foam. (looks good & feels right) i can't use radio without it now, & it's the first thing i put on new radio. Just got DX3RPro first thing was to set trigger up with foam/d/sided tape trigger gap eliminater !

Yep i had the same problem with my Futaba 3PMX, because of my small fingers there was always a big gap to when applying the brake,
I just used a rubber hose i found in the garage that fit nicely and the rubber stops any finger slippage.

Beth.