Receiving a Design Award for the one-hand car-conversion I built (my left hand on joystick-control, early Lightwriter on lap).
Car-conversions were a big part of my younger years, Lightwriters were a sideline.
I was shortlisted by the Thalidomide Trust to do their car-conversions.

Below: A hirsute me with the very first Lightwriter. Click image to read the text.

I was on Tomorrow's World a few times, after 3.00 mins of other stuff I'm on  ...

I had a wine business, which was fun.
I was involved in the design of a public toilet with a carousel theme, which was even more fun.

At age 19 (I became disabled at 21), I built a very small 'monkey-bike' between leaving school and going to University. 
Design specification: to fit into a car, and nip around cities when I got there.
Step1: Buy a BSA scooter for £5. Step2: saw it in half. Step3: Weld it together. Step4: Learn from experience that motorbike frames should be brazed, not welded ... it was a fast machine!!

I built a wheelchair based on a car-seat (I can't remember why, or where it is now).

I applied for Planning-Permission to put a large helium balloon on Parker's Piece, Cambridge.
Permission denied, but the 'research' was enjoyable (I visited this one in Paris).