[AmityvilleHams]

I'll also add that no matter what you do, any plastic cutting/melting(if you use a wood burning knife which is an option)/etc should be done outside. The last thing you want to do is be inhaling the fumes yourself or have anyone else(hamsters included) inhaling the fumes, particles, etc that can come from that process.

Zip ties as others have mentioned will work just fine but make sure you have strong scissors or something sturdy to cut the ends with. Make sure the cut end isn't on the inside just for hamster safety, and if you have the option of using pliers to tighten the zip ties in my experience that does at least make you have less of a chance of getting sore hands. Wearing gloves for protection when possible is ideal, though personally I found the ones I used for a different(failed, but similar concept) project just got in the way - and because of that I ended up with fairly sore hands!