DIY Wheelchairs Are About Solutions
The primary purpose of building a manual DIY Wheelchair is to solve mobility problems. If you currently don't have any wheelchair mobility problems, then you don't need a DIY Wheelchair.
I think that DIY Wheelchairs are most practical as (1) your auxiliary (backup) wheelchair, (2) special purpose wheelchairs such as for Off-road, beach, snow, gravel/dirt, road races, etc., or (3) for emergencies. Note. If someone doesn't have a wheelchair, it is an emergency. Hopefully, your primary wheelchair is a well made and properly fitting, non DIY wheelchair.
DIY Wheelchairs are intended to compliment and increase your mobility solutions, not to replace what you are currently using unless absolutely necessary.
Specific DIY Wheelchair Mobility Solutions
Quad Wheelchair.
Trike Off-road Wheelchair + DIY FAT Tires.
Quad Wheelchair + Urban Front Attachment + Rear Wheels with 26" Bicycle tires OR Trike Wheelchair
Quad Wheelchair + Nature Front Attachment + Knobby Tires OR Trike Off-Road Wheelchair.
Quad Wheelchair with Urban Trike Attachment + Rear Wheels with 26" Bicycle Tires OR Trike Wheelchair.
Quad Wheelchair + Nature Trike Attachment + Knobby Tires OR Trike Off-road Wheelchair with DIY FAT Tires.
Quad Wheelchair + Urban Trike Attachment + Front Carrier OR Trike Wheelchair.
Beachbum Wheelchair in Reclining Mode.
Quad Wheelchair + Nature Trike Wheel + Knobby Tires OR Trike Off-road Wheelchair