I had one of the SmartCarry knock-offs that are available on Amazon. While it wasn't a primary holster, it mostly did what I wanted it to do and it was what I used for jogging. Unfortunately, I lost it earlier this summer, and I didn't miss it much until I had to share a hotel room with someone for a week. I was able to always be carrying, even in pajamas with my Comp-Tac (without the other person knowing), but this deep concealment holster would have been much easier and more comfortable. Rather than buy another one, I decided I'd just make my own. I used scrap material I had laying around so it doesn't look pretty. I did everything from scratch, so there are plenty of improvements to make on future revisions, but it more or less works exactly the same as the one I had.
Here is what I bought off Amazon: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Here is everything I used. Double layer of thin denim in the back, sandwhiched over plastic as a moisture barrier, double layer of heavy denim in the front (helps conceal the outline of the pistol), medium duty elastic waistband material, doubled up for strength, heavy duty velcro, some standard binder material.
All sewn together. I spent a lot of time with a protractor getting the curves exactly the way that I wanted. I thought it'd look a little slimmer and hold the gun a little better. In the end, it looks exactly like every other crotch carry style holster I've ever seen. Oh well. Also, I bought a binder foot for my machine thinking I'd be able to quickly, and perfectly, install binding, but as you can see it didn't work out. Still have some learning to do on that part but my sewing life coaches have provided good tips for next time.
Glock 23 on left, CZ 75B on right. This turned out larger than I thought. I used all my pistols to make sure they fit, but using the CZ as a guide to make sure it covered the grip made it very large and as a result it swallows the other, more realistic, sized carry guns.
Can't even see the M&P40c when you drop it in the holster.
So, I learned a lot doing this project, but overall it was pretty easy. The most notable things I learned are that 1) The reason SmartCarry and the other brands use a duckback material as a moisture barrier, is because that plastic makes it sound like you're wearing an adult diaper, and 2) you probably aren't going to be deep concealing full sized pistols, so it doesn't need to be nearly as tall. There are many other improvements to make, but they are better discussed once I actually have made the changes.