Epoxy or Urethane High Build... what's next for me?

Like Dartfreak75, I have used SPI epoxy primer, and it is GREAT! You can apply filler or 2K primer over it without sanding as long as it is done within their specified window of time. I used SPI epoxy thinned with urethane thinner the other day as a sealer, before doing base/clear over it. Turned out slicker'n cat poop on linoleum! :D