Hey PH.
This is not a “how-to” or anything, but I’ve created several remotes of my own.
Each time, I’ve used the PCB from an existing remote and created a new body in CAD. I have arthritis in my thumbs, so it hurts to use the Thumb-wheel remotes for more than a few minutes. And the only brand that uses a pistol-grip style remote is Evolve. I have an Evolve, and Im not impressed.
So I set out to make my own pistol grip remote.
I immediately ran into an issue. Because to have Index finger Throttle and Thumb Break, I would need 2 channels. But the Thumb-wheel remotes use a single channel for both throttle and break.
After some thinking, I figured I could just do it RC Car style, which has throttle and break on the same channel. And it’s just a Cam mechanism so its wasn’t too hard to figure out. Most Eskate brands on the market, the ones that don’t make their own custom ESCs, just use off-the-shelf ESCs, so you can pair many different off-the-shelf remotes to them.
Anywho… Pictured here are 3 of my DIY Remotes. They all have integrated Green laser pointers, the 2 clear ones also have built-in Garage door openers too. 
The small one on the right was made from one of these:
The middle one, the is the one I currently use on my Propel Endeavor 2 GT, was made from one of these:
A Look inside:
The lower white one on the left is different tho. This one was for a VESC based project, so it needed its own receiver. Because of that, I was able to program several channels so the “Index/throttle, thumb/brake” thing was no longer a problem. No Garage opener on this one, but it does have wireless charging.
For that one I started with a Maytech remote:
Dunno if any of this helps, but there ya go. 