I bought a bottle of acrylic-based surface sealant a while ago on Amazon, and it hasn't run out yet. Great for circuitboards, receivers, etc. Basically 90% of stuff that needs waterproofing. Not great for anything that needs to flex, like servo wires. That's what skotchkote is for.
I print a tray thats big enough for the board/device/whatever and deep enough to 100% cover any bits. Then I brick it in epoxy as @Beaver said. I stuff my receivers with E6000.