It's easy to protect your puzzles after you've spent so much time putting them together! Just add ArtResin :)
Glue your puzzle to a thin wooden board, such as MDF or masonite. I just use craft glue. Then prop your piece up on some stands and make sure the puzzle is perfectly level. ArtResin will self-level, so it's important to make sure the piece is not wonky before you pour it on!
Then just mix up equal parts of the resin and the hardener. Stir for 3 solid minutes, and then just pour and spread over your puzzle! You can let the resin fall over the edges.
If you notice bubbles coming up from between the puzzle pieces, don't worry. You can get bubbles out with an Artist's Torch. Just run the flame quickly over the surface and you'll notice the bubbles easily coming to the surface and popping.
Then cover your piece overnight to allow it to cure, and you're done! A perfect finish to protect and display your prized puzzle.