What custom project did you always want to do?
I have two:
1 - Remington model 8 in .25 Remington. Color case the receiver, fire blue all the receiver screws, carbona blue everything else. Add in exhibition grade wood with simple but elegant checkering. Install a Deeley & Edge forend release on the forend to make takedown easier. Add a trap door, steel butt plate that's case hardened.
2 - Make a reproduction of W.D.M. Bell's 275 Rigby and keep it an open sight rifle rathern than ruining the classic lines with a scope.
Kimber Montana, .358 WSM
Oooh, MAMA!