Wear gloves and you'll be fine. You mix it at a very slow speed, so there is little to no chance of spilling. Some resins may smell, but you'll want to leave it in a dark place, out of the way while mixing, so there shouldn't be any problems.

The ingredients can be very cheap. But I haven't done enough research into what they are and where to get them. I have talked to a chemist from one of the big resin companies, and he says the material is throw away to them, a couple of bucks a kg to make. The cost is in the research, after-support and machinery. The cheapest company I've found selling pre-made SLA resin so far, will do it for less than $25/KG if you purchase 200kg at a time.

I've thought about making my own, but the main thing I worry about is consistency. I don't necessarily mind purchasing a large mixing VAT, but I'm not a chemist and I can't be confident enough that each batch I make will be exactly the same and compliment the previous.

Professional resins can cost $400/kg but when we can easily get DIY resin for $25-50 kg (which is the only level which we can realistically hope to achieve without proper machinery and knowledge,) how much are we realistically going to save by making our own?