The rear frame is completely welded ... it bows slightly (the open ends point slight inwards). I had to make the middle pieces 1/4" longer because the plans call for using 1-1/2" tubing ... and I made the mistake of getting 1-1/4" tubing ... and then cut the tubing specified for the lengths for the bigger tubing. Oh well. So, lots more welding, grinding, and re-welding.
I completed and welded on the gusset under the seat tube area ... put a 3" metal pulley on there (found cheap at Lowes) ... the grandkids will just have to live with the extra noise ... and not being confident about the joint between the main tube and front tube ... I welded a strip of re-enforcing metal to strengthen that. And I stuck the front forks on just for fun.
I did cut 3" off the length of the seat tube ... because I intend to put 20" tires on the rear ... and a 16" tire on the front.
I'm making plenty of mistakes on this 1st one ... by the time I get to the 3rd one, I should have a good trike for myself.