Having owned a '68 VW Beetle for many years now, the main problem I encounter is storage., or rather the lack of it!!
The glove box is great, unless you keep your stereo in it, the wire rack thingies are great, but having had one, you do find that stuff slides out of the gaps and the drinks holder just isn't big enough..
And I just don't have a 3D printer or a Laser Cutter or anything high tech. I have my imagination and a Bandsaw.
Step 1: DRAWINGS:
I start by sketching out exactly what I want from the storage box and thinking what I want it to hold.
Drinks, phone, sunglasses, show tickets, change, chewing gum, sweets, bits and bobs.
The storage box is the picture on the left, the other one is an idea to fit in the ashtray compartment.