If you are building your own custom router table you are likely using a wooden counter top for the work surface. A router lift will always have
Ultra-cheap Router Lift : 6 Steps (with Pictures) - Instructables
Router Table with Lift-50-200
Create Perfect-Fitting Openings for Router Table Insert Plates – Infinity Cutting Tools
Routing Template For 9-1/4 X 11-3/4 Insert Cut Out – JessEm Tool Company
Routers & Router Lifts
Kreg Router Lift - Precision Router Table Lift
SawStop Router Lift, Cast Iron Table, Mobile Stand, Fence & Bora 3.25hp Router
Kreg PRS5000 Precision Router Lift
Ultra-cheap Router Lift : 6 Steps (with Pictures) - Instructables
Rockler, Pro Lift, Router Lift, Model 52429, Quick Gear, Snap Lock
Kreg Precision Router Lift (PRS5000)