If you have an old inflatable mattress, consisting of several independent sections, it is easy to adapt as life jacket for boating. You will have to sacrifice one of the middle sections, making it T-shaped hole for threading of the head. To fix the other slightly inflated section around the torso using the waist belt and extra lacing.
Recommend to read
BIKE LOCK
A small segment of a steel cable clad in a tubular plastic case, with their ends included in a metal cylinder smaller than a hockey puck. This is a bike lock designed to prevent...
TANDEM FOR TWO, THREE, FOUR
For a basis we took the road bike (with "women's" frame), set on it a longitudinal beam of the two aluminum profiles-"parts" and fixed on the beam two seats with backs so that the first...