XRAY - Model racing cars

i'm trying to balance my T3 2012 car so it is more consistant i have borrowed balance tools to put in small chassis holes front and rear of chassis to do left/right balance of car but how do i find middle of chassis for front/rear balance of car has no holes on the left/right of either side of chassis ? thanks

Scales or get a piece of right angle metal (L bracket) and lay it on it's side, you would need to mark off the exact center with a silver sharpie or tape so you know where to line it up.