best tool = care full planning and skill full execution .... not a swag ....not a snafu or a fubar .....
2. let the glue dry
3. a new sliding chop saw but you have to watch the rotation of the blade.
4. a table saw set up with a sanding disk watch for rotation of disk.
5. rotation meaning while spinning it does not naturally pull the rubber off the rail but towards the rail.
just the basics more tools needed if changing pocket size opening
Some people use a fillet knife to cut the rubber, some use long utility blades, but there are other various methods, as n10spool mentioned. When using a blade, I like to use a little bit of soapy water as a lubricant.
Keep in mind, it can be difficult to cut the rubber without having a secondary finishing step, before applying a pocket facing. Of course, this all depends on the quality of work you are aiming to achieve. Most mechanics on here prefer to cut the rubber a little long, and sand it down to the finish dimensions.
It is possible to use a miter saw, as n10spool suggested, but you have to be extremely careful. If the saw catches the rubber just right, it'll tear the cushion, and maybe your fingers, into pieces.