When this was talked about last time I went and got one of the non spill stainless steel vacuum insulated mugs which was mentioned...
Route channel no problem...
If you came up with a safe design on the heater I would consider it.. but off hand that sounds dangerous...
I could make it adjustable for several sizes... but seems better to pick a good mug and make it to fit it well...
The other items ? I don't want you spending that much time looking down between the seats..... ... keep your eyes on the road.....
For my car I was planning on making a matching shift knob...

Also the possibility of using pewter for the inlay....