Dubs Chops,
Resin is what I make 90% of my molds out of. They make a great one sided mold. The only things you need to look out for is the srhinkage and the warping. The shrinkage is on of the reasons it is not to good for two sided molds. The warping happens when the mold is too thin and gets hot. I always try to make them about 5/8 to 3/4" thick. Also, if you plan on pouring a couple hundred baits at a time, allow for cooling tme for the mold as the resin smell will come out when they get hot. Hope that helps.
Zbass