Velorex was a Czechoslovakian company that specialised in building cars for disabled drivers, particularly those that had been injured in WW II.  To save on costs, a waterproof fabric was stretched over a tubular frame, the 3-wheel vehicle being powered by a 250cc Jawa engine.  Velorexs were made between 1951 and 1974.

1951 Velorex. Model by Tober Models (Bill Barnes)
1966 Velorex 16/350. Model by Abrex