Quoted from dzorbas:One thing I would suggest simply because my hardtop went down slightly off in one small section it to add a bit of black paint around each of the inserts similar to the original keylining. This will keep the bare wood from being visible through the clear section of the hardtop should you miss slightly.
Take a closer look at any original playfield. The black keylines are never perfectly center. If you add black to fill in the bare wood spots, your keylines will be inconsistent thickness.