That is quite the question. One which I have pondered many times myself.
Firstly, I would NOT suggest using Projection. To hold an item in place with projection you would actually need to be holding it IN PLACE within the alchemy circle. This... would destroy your astral body, as what happens to things within the Fount and Filter when the transmutation is complete? >.> Nothing good. They are stripped of their very identity.
However, you could use Air Reimancy to levitate objects! Maybe have some glyph set-up with Air Reimancy involved and see how that goes? Of course, levitation via Air Reimancy is very djed costly, so even setting up one transmutation that uses this method is going to take some work/skill in the magic itself.
Some non-magical means of setting up an upright alchemy circle could be, as the article suggests, pedestals. OR you could suspend things on STRING and it wouldnt effect your reaction since the string/rope is present in both the Fount and Filter. For very heavy objects you want to lift, you can use a pulley system XD but I think that might take some gadgeteering and understanding of physics.
OOR just get really good with Air Reimancy
Im sure there are other ways, but those I do not know of.