I agree with Paul there. I really like my Dremels (I have both corded and cordless) and used them all the time for sanding and cutting polystyrene. My [hobby] life changed after getting them! For resin however, I would not use it due to health hazards.
Your mentioned methods, nippers, sandpaper, razor saw and the underwater technique, sound better and safer for resin.

Regards,
James

Most Hobby Resins use a fairly benign chemical compound, and are far less toxic than most paints and solvents-- including aqueous based paints, unless you have an allergy to plastics. It's about as toxic as flour, sawdust or road dust. However, in large quantities suspended in the air those materials can be bad bad for you too, and you should wear a protective mask when around any material in air suspension for long periods of time. If you are occasionally removing a small part from a resin block, there really should not be a problem using either a razor saw or a Dremel disc saw depending on the saw, but both methods release dust into the air. I use a 220 tooth fine disc saw in my Dremel at about 15,000 RPM, which generates less dust than a hand razor saw--as the disc saw cuts faster and finer as opposed to the more coarse cut of a razor saw. This has an added advantage of being able to get closer to the part, which means less sanding later which creates even more dust. Now, if you use a Dremel Cut off wheel, which is really compressed silica sandpaper, you'll generate lots of dust-- and that's not what you should be using to cut resin with. Depending on the blade, power tools create large amounts of dust at high speed, but so do saws of any kind, so don't feel that you're safe just because you use a hand saw cutting at a slower speed. So, if you are in doubt about dust in the air around you, use an MSA approved dust mask. My advice is, if you paint, sand, or generate large quantities of any particulates using a tool of any kind, that remain suspended in the air, wear a mask. I have some experience in this area, since I spent 25 years working in various toxic environments while wearing masks. But I worry far less about cutting resin than I do about spraying paint or using solvents. So far I haven't grown any extra fingers on my hand yet!
VR, Russ

Polydactyly can be advantageous when aligning some of those cumbersome multi-piece assemblies found in today's more detailed kits.

Ha Ha-- I was wondering if someone would comment on my comment! It's not the extra fingers you need though-- it's the extra opposable thumb that would really come in handy!-- if I could grow on of those it'd really help with holding those small parts! I could even sand and cut parts using one hand! Imagine-- if you had an additional opposable thumb on both hands what you could accomplish-- you could write letters, type, talk on the cellphone with one hand, while building a model with the other-- better yet, you could build two models at once, one with each hand! Hey- do you suppose all those space aliens evolved because they were doing that?
VR, Russ