LSA can exist in pure form or as crude extract from MGS or HBWR seeds, but might be a little less stable that way. Actually there exist plenty of psychedelic legal high capsules that are mainly trippy because of extracted LSA, and the other ingredients being minor supplements that are supposed to synergize but is relatively unimportant. So you don't have to extract LSA if you just want the caps - if you do it, probably good if you enjoy the chemistry anyway.
Those are the main ones indeed that Weltmeister listed, and for every one of those you can find an extraction thread listed in the PD Index (link at the top of the page)... although bufotenine extraction is a little more obscure and not as well-represented. Bufotenine or common impurities can have particularly unpleasant physical effects and there is some discussion over whether to make calcium salt etc. It's definitely not something to take in public though, neither is 5-MeO-DMT or DMT.
I don't really get what would be wrong with putting a blotter in an (opaque if it must be that stealthy and you want to pretend it's medication) capsule though.