Gloomhaven Flying Monster Standee Riser with Peg

I added a peg and holes to lane182's [Gloomhaven Flying Monster Standee Riser](https://www.thingiverse.com/thing:3008255) so that it no longer needs to be glued together.

It's a very snug fit between the peg and the third piece, but it will fit and hold well. Be firm yet gentle when pushing them together and make sure the peg and holes are clear of any excess plastic.