depends on how successful the first attempt works out. i will post the successful result as a individual build log, but

I have a different type of frame assembly planned, hopefully making it easier to assemble a heavy duty frame, relatively accurately. but if it goes wrong, i can disassemble and get it wielded. The idea being make an accurate bolting jig, about 200mm long. a 5 star pattern and a 3 bolt straight line. Start at the center of each length for the first bolt pattern. then accurately measured outwards for the next ones. the advantages being ;
1. your only relying on each 200mm section to be square for you bolt patterns.
2. Your not relying on your cut lengths to be totally square at the end ( perfectly )
3. As you assemble the frame, you will pull out most of the surface twists in the metal, ( as long as you have a proper assembly plan ).

then things am still trying to work out,

1. optimum bolt width/distance between bolt patterns. ( material is approx 10kg pmtr, 120x60x3.6 )
2. No of positions to plan for threaded bar/nuts to assist in initial lining up

Once initially assembled, i can then decide what parts need welding or maybe brazing, and if i have made enough places for triangles in the corners. If done correctly, the final bits bolted on should meen the frame is very close to am accurate box, and very strong. But, if am not accurate enough with the bolt patterns, it will be all over the place.

I will post any mistakes i make on this one, as i go along ( and ask for help ). then post a seporate one for the completed sucsesfull build.
Am currently considering building\buying\converting a mil to get the accurate bolt patterns. as i will need this for the head designs i have in mind. But, ther are a few companys near me that can mill metal to the accuracys i need. So i need to get proper prices first from them.