I use Sketchup. The learning curve isn't steep on such things as my flashlight holder. You design the profile and then "extrude" it to the length you want. Other stuff... sure, but there are lots of YouTubes.
I must have missed the interview about cup holder space. And yeah, Sheldon talks about the engine and tranny and frame and suspension, etc, in several videos.
Teardrop campers?
It's got a queen bed with an 8" dreamy mattress, heater, ceiling vent fan, solar charging, weighs 1300 pounds, and tows like a dream.
We use it a ton.