The real reason is that this is stuff I have laying around already.
It is a good question and I will look into physical integration. I have a lot of arduinos laying around too but I’ve never tried to integrate with my iPad (besides WiFi). I am not a member of the Apple mFi program so physical integration with an iPad I think is not that simple. But maybe things have changed since I last looked at it.
Yes BT integration can be tricky with iPad and ESP32. I wrote a little iPad app to make this demo work so the iPad would accept it as an HID. My iPad is old so I think if it works with this version then future versions of iPad should be easier/better.
I have 5 buttons working just fine so far but am planning to test out a 5 way analog rocker tonight to see how that goes. My plan is to make it drive the little orientation cube. (Which is what my 5 button config currently does). It is pretty limited what actions can happen with Shapr3D right now but I expect they will add more key binding as time goes on.
The prototype is currently running off a rechargeable battery and/or can be plugged directly into USB to charge while using it. I for sure lean towards wireless for something like this but I have nothing concrete in mind yet. On my laptop my mouse is BT so seems pretty reasonable to use BT. But honestly, I am currently just using the path of least resistance to see how usable something like this can be with a primary focus on the form factor of the human-to-machine interface. Processors, code, etc I think is a distant second to that at the moment for me.
One thing I’ve not come to terms with is to keep this as a DIY level or go for super-efficient custom hardware. I like the idea of the DIY level.
If you get the ATiny thing working I would love to see what you do there.