Ha ha - the Ponal will last for ever. Yes it is safe to chew once dry, but best not to have any glue visible - I just wipe any bits off that seep out when you stick something together, but you need to wipe it off when just done or it sets quickly. Takes about 24 hours to set firmly. I had to prop things in place until it was set or they just fall apart until it starts to harden.
I wouldn't make a fleece hammock to be honest. A lot of hamsters will just chew it and then it's a risk if they swallowed any. You can buy a grass hammock though that's safe to chew. Amazon and Zooplus sell it. I couldn't use it as I'm asthmatic and I was allergic to it! Anything grassy .......
https://www.amazon.co.uk/Natural-Ham...=grass+hammock
You can also get chill and chew mats made out of woven hyacinth - a bit softer but less flexible - and some people have turned those into hammocks.
https://www.amazon.co.uk/Rosewood-Bo...ill+n+chew+mat
I did try our last hamster with a Fleece hammock but he immediately tried to chew it (they forage for nice nesting material) so had to take it out again and he then had a major tantrum about it. Fuzzbutts sell very good fleece hammocks for rats and some people use those (chinese and dwarf hamsters seem less likely to chew them) = but I also think the eyelets for hanging them can be a risk (a foot getting caught eg) there have been many hamsters found hanging by a broken leg from a hanging roof toy - chains are particularly risky. There are usually ways round things with hanging them though.
I have the Fuzzbutts mini snooze cube - but don't use it in the cage - I use it for out of cage time and for the hamster to hop in and out of to lift him out of the cage (I lower it through the top and he walks into it).
I did have it in our last syrian's cage when he was very old and incapable of chewing much!
http://www.fuzzbutt.co.uk/Homersnooze-6a/