Use a polyester filler to rebuild rotted or damaged wood after applying wood hardener. (Minwax makes High Performance Wood Filler, or use Bondo for cars!) You can mold and shape it to match the original wood profile. It takes paint well and won't rot.
10 DIY:: Amazing Kitchen Updates on a Dime !!
Refinish Your Kitchen Cabinets with Rust-Oleum Cabinet Transformations. An $80 complete kit so you will never have to prime or have chipping cabinets again! Great alternative to expensive kitchen renovation.