I'm in the middle of a very similar project myself, and although its only my second pouch, its working out really well.
I created a two part plywood mould - the first has the inner plug glued to a baseboard and sanded smooth. The second is a plywood board with a hole cut out to fit over the plug with enough extra space to allow it to be pressed down without scratching the leather. Again all edges and sides are sanded smooth.
I soaked my leather in lukewarm water for around 15-20 mins, then placed it onto the mould then carefully pressed it down manually first, then used the second part of the mould to press it down all the way. Once happy that it was moulding correctly, i attached a couple of spring loaded clamps to hold it all secure. The following day i released the clamps to check it was okay, ad found that one side was more curved than i wanted, so because the leather was still quite damp, i was able to manipulate the plywood and the leather to tighten up the side that needed it. Then back on with the clamps and left to dry for another couple of days.
I was so taken with this method, that once the leather was dry I was able to trim it to the size i wanted and then draw around the entry profile on to a template from which i made another set of moulds for creating a cupped lid. The two work together really well. And it worked so much more easily than i expected.
Cant wait to finish it properly
Pouch body being formed in mould
Lid being formed - this needs to fit snuggly over the body pouch so has a curved front edge, and i left the back as a long flat piece so it can be shaped and creased to form the rear panel
Not shown is the third flat piece i used to make the lid top flat. This picture shows i quite curved, so i placed a sheet of plasticard over the wet leather and then a sheet of plywood on top of that which was weighted down to give the flat top seen in the next image. The plasticard was to prevent any wood grain from being impressed into the leather
the two halves side by side
awaiting stitching and finishing - but the idea is pretty clear.
adam