Your „do it yourself“ handcycle
The concept or the idea are essentially 2 points:
Use parts of an old bicycle and knock over the wheelchair to sit on the backrest (see sketch). (This let you to sit deeper.)
A bit more concrete:
Allow handcycling as „do it yourself“ , „how to..“ or open source, especially for wheelchair users without financial possibilities.
This requires a wheelchair and an old bicycle. At the bike you have to cut off, weld and screw to get a Frame.
This is screwed to the backwards knocked over wheelchair.
The end result should be a handcycle at almost no cost (apart from the old bike and the cost of labor).
You can find details under „Versions“.