I have another batch of 6 done, and am down to about 30 more to do (mostly smaller ones) and then I will be done with the monsters, bosses, and warriors. I’ve tried a few things to keep them on the wall other than thumbtacks without putting holes in walls, but I’ve found that’s the only way to keep them there. I tried glue dots, poster tack, double sided foam tape, and even masking tape, but they fall off eventually.
I have settled on Sequin pins since they are small, cheap, and a little longer than thumbtacks. They are a total pain in the behind to push into the wall (I use a pair of pliers), but once they are in, you can hide the head of the pin in the hole of a bead, and you can put them where they need to be to hold the perler creation flat against the wall, where a pushpin would look out of place in the middle of it.
I plan to have this complete by mid October, and I might even make a big piece based on the bridge crossing scene to add to it. I love it when a plan comes together.