[AmityvilleHams]

Anything that's cutting or drilling plastic should really be done outside as it will all lead to producing fumes and such.

In general a tool that produces heat would cut through plastic much smoother than things like drills that'll have a risk of cracking the plastic and similar issues. Even a cheap wood burning knife can work. I remember even hearing about people heating up knives and using that to make holes in the past, but that would be difficult to do safely with plastic fumes and such in mind.

As far as tape goes, you never want that to be on the inside of a hamster cage regardless of type - another great reason to keep mesh on the outside. Duct tape is the common solution and comes in a nice variety of prints and colors. I don't know if anyone has tried something like washi tape, but it is entirely possible that could work too - it might take more than one layer though.