Just to clarify I did not say you shouldnt use a jig,you should if possible ,just relating my experience with mine and it turned out good,it can be done on the cheap if you're determined and have the materials and the skills,I also built my own backbrace and all in my garage,would I do it again,probably not when you can buy one to size and with a backbrace already with perches ready to go for a decent price from moser but at the time I couldnt afford to do that so I made my own and by my own mistakes and sucesses and most of all by my own rules,and if you think about it the 3rd member and the axles are your jig....just got to be smart enough to figure it out,if I can,anyone with the right materials,mech and welding skills could duplicate it fairly easy...but if you have access and can get a jig by all means do so probably save you a bunch of time and agravation and it will be 'professionally done'
