Beginner working with plastics!

[trachael]

So many questions!  I am trying to reuse some prescription bottles as Christmas ornaments, but my design is requiring that I cut a section out of the side of the bottle.  Any suggestions on a type of knife?

I experimented with what I had available ( a likely dulled pocket knife)  and it left some very jagged edges.  So would filing or melting the edges be better for getting  a smooth surface?

Finally-  any suggestions on a drill bit size if I were to drill a hole in the top to hang it?  I tried to just hold it over flame to soften it and then twist the knife through- but this is quite tedious.....

[Onyxnox]

Drill bit size - depends on what you are putting through the hole to be the hanger, and what you are using as a stopper - fit your bit to the size. 

I would file the sides myself - with something like a dremel.  Make sure to wear eye protection and a mask if there is lots of fine dust.  Melting could do it, but you could also scorch the project, or cause damage that can't be undone, and if it is less controlled - besides, you may end up with globs you need to file off anyways.

[lovesclutter]

Yes, and if you melt, that needs to be done in a VERY WELL VENTILATED space.