I decided to try a tuckable holster this time. I roughly pre-molded the front side, before sewing--still using the foodsaver bag, but with a piece of scrap masonite in the back instead of the back side. This complicates sewing just a bit, but results in a smoother back against the body--I think the trade is worthwhile. I also went with very wide radius curves, avoiding any small pressure points except at the rear of the slide where there really isn't an alternative. Once the sewing was done, I re-wetted, and did the finer molding. Clips are from Comp-Tac, left over from another project. I need to find a good substitute, because their addition roughly doubles the material cost of the holster. Screws go into T nuts, meant for woodworking with upholstery leather as a backer.
This is comfortable enough that I may begin carrying my 4"XD more, and I may make a version for my 3". Not too many improvements necessary, and not enough to justify making another for this gun--the only thing I am likely to significantly change in the future is the attachment point for the clips--Holsters are more tuckable if the screws are in the bottom hole of the clip, but currently that position leaves the grip too close to the belt. to be useful, I'd also need to change the way it attaches if I use the metal clips that I can easily obtain.
There are a few holster makers that don't like tuckables, and say that a gun under a tucked shirt is too slow to get to to be useful. I somewhat agree with this, but I prefer clips, and most clips are tuckable. You don't have to tuck, and the design gives more clearance between the grip and holster, allowing a lower position. I have also had a couple of times where plans changed, I needed to remove a layer of clothing for comfort, and an untucked shirt would have been conspicuous.