so this is a long shot.  I've got a buddy (super nice disabled combat vet) who has a 3 year old son with cerebral palsy.  he is looking for advice / plans / assistance on modify an existing trike or building a trike his special needs son can use.  these trikes can be bought on amazon but run $800 - $1200.  anyone in the community have experience with such or can you point me in the direction of help?  thanks in advance.