Per your request, attached is a picture of the chair that my son designed and built for his 7th grade, Science project. The assignment was to design and build a functional chair using recycled materials.
The framework is made entirely from old wheels that were loitering in my worshop. With the exception of the rim for the seat base (which is a 20", steel, BMX rim), the remaining rims are 26" alumumunum ATB rims that have be cut and reshaped. Don't worry, they were all cheap rims from trashed X-Mart bicycles. The framework is held together by 8 self-tapping screws and 4 tie-wraps.
The only wood product is some peg board used in the backrest and seat. There was contemplation of cutting the flange off an old hub and using spokes as the seat and backrest, but there was a "comfort" element to the grade. So the pegboard was overlaid with some underlay left over from a recent carpet installation and an old dress supplied the fabric covering.
The anti-scuff covering on the bottom of the legs are made form old inner tubes.
The chair is light and very strong. It is solid, even for a 200 lb person.
The whole process of working closely with my son was extremely satisfying, as this was his first foray into my field of mechainical engineering. It was quite challenging for me not to tell him what he do, but try to guide him by asking him questions that would cause him to think and logically come to workable concept. I had suprisingly little direct input to the actual design.