Best Way To Cut Rubber With Hand Power Tools

I'm trying to find a different way to cut rubber boxes than our standard method. The wall thickness varies from a quarter of an inch to a half inch depending on box type. Currently we trace the outline of the cutout and then use drills and jigsaws. I want to try either a handheld router or spiral saw (Rotozip) fitted with either a router bushing or top bearing bit so as to follow templates. I'm leaning towards the Rotozip with a jigsaw handle fitted with either of the mentioned guide accessories.

I've read some of the CNC posts on the subject but for the time being we're using handheld power tools. I think freezing the boxes is out as that would increase the production time. So this leave bit choice and spindle speed. A Rotozip 5/32 bit will cut the rubber but I've definitely had instances of smoking at the bit.

any suggestions?
thanks

if you froze several at a time say overnight it shouldnt effect actual machine production time.
a bath of co2 or liquid n would be fast.

Are you using anything as a coolant or lubricant? Soapy water works quite well with rubber.

I have not done a lot of machining on rubber but I did determine that a very sharp tool with a large top rake worked best. Maybe you could try the micrograin carbide endmills with a very high helix angle that are made for aluminum. They do have a very sharp edge and the helix angle effectively gives them a large top rake.

I woul try running at a modest speed, 2000 to 4000 rpm and use a rich soap solution as a coolant.