Bear can be a "bear" to get a hold of at times because he spends a great deal of time at the CNC mill making molds for all of us. the presto pots he builds will hold a gallon at a time. the stirring units attached work incredibly well at keeping glitter and salt suspended. Bear is probably one of the most honest of the mold suppliers we have working for us, and there has never been a problem with any of my orders with him.
as far as the yellowing plastic, keep an eye on temperature and how long you have it heated for. you will want the temp as low as your process will tolerate and you want to use your plastic as fast as you can.