@Duncan_Gunn the resin has two main pains. #1 - Finished prints are still coated with uncured resin and to post-process them you need to get them from the machine to the cleaning station/area. If you’re careful that’s not that big a problem, but just a couple of drips leaves a very sticky surface and if you don’t notice them the resin will transfer to fingers, clothes, etc.
#2 is much more an issue. You buy resin in bottles or cartridges but it needs to be in the print tray to be used, so it’s all about how it gets from the bottle to the tray and, more importantly, how do you deal with the trays that have resin in them? You really need a dedicated tray for each resin, so you’ve got to store them somewhere flat and safe. When a tray reaches the end of its life (possibly less than 2L of fluid later), you’ve got to drain out the unused resin and dispose of the tray somehow.