Fixing plexi to PAL is easy i just used screws. The pointy type that can be added with a power drill. Also making holes in plexi can be done with a hated metal or with the powerdrill itself. Also you should make the holes in the plexi before adding the final screws.
Now plexi on plexi... I just used a general glue and a corner type of plank. You can buy them for about 5 euros 2.5 meters long. This was done for reinforcement of the plexi because its only 2mm. The screws in the PAL are what is holding it together.
I like the fact that now she is sleeping in one of the houses rather then unddr the bidge like a homless person because she has 3 of them
I will try to adddress the open pal bit in the enclosure. I was thinking about that. Anyway after about 2 weeks i feel that the calmed down. She is finally gaining some weight from 45g to 50g. I like her at 50g