Ok, heres how to make a DIY lobster back bend:
1, Buy some pipe your going to use, this being stainless steel, you can use a wood cutting mitre saw for alloy pipe much easier but you wont get the same look as stainless.
2, work out the distance, you have to work in and need the bend to fit,
in my case it was 90mm by 90mm
3, set the bend out on paper(best thing i found was MDF sheet).
4, ok this is where it gets a little tricky, take the life size measurements from that scale drawing, So if your using 3" pipe make shure the ends of that bend are 3", once you get the outside dia from the bend and the angle of the bend being 90". put all these measurements into a program found here (http://www.tyharness.co.uk/lobsterback/lobsterback.htm)
What this will give you is the amound of segments you want and a template you can transfer over to the pipe.
5,once you have the desired pipe and abount of segments you can transfer the measurements on computer to paper, what you see there is the measurement from the centre out in incriments of 10mm.
6, transfer to a template, i used the cheap plastic cutting board you buy from the shops, its sturdy but not to flimsy, just cut with a pair of scissors.
7, Tape the stencil together while on the pipe, much simpler this way,also not to tight.
8, Now your ready to mark it out on the pipe, 1st put a straight line accross the pipe, this will be your center line so you dont get lost with the stencil markings.
Once you have marked the 1st segment, blow on it or wait for the marker to dry or you will smudge the line out, now spin the stencil around the pipe so that the smallest part of the stencill matches with the widest part of the previous marked segment, also remember to leave a slight gap between each segment for the thickness of the blade and other discrepencies.
9, Once you have done a few you are now ready to cut, i would say about 10 is enough till you need more, otherwise you waste it.
first things first, wear thick gloves cause it gets hot, use a grinder with a 1mm cutting blade, buy about 10 because one blade is good for about 8 full cuts,
I layed the pipe on sonething with the stand having the ends holding the pipe in because i turned with one hand slowly while cutting the pipe, dont force the grinder, let it cut, if you keep it at the angle of the line at all times you should get a nice cut, but the 1st few always turn out bad, also wear Ear protection and Saftey glasses, if you get a bit in your eye, you will have to go and get it drilled out, they hold your eye open while your awake, never happened to me but i was told thats what they do.
10,End result, your peices should come out like this, also for a better weld its best to grind each end of the segments flat on a bench grinder, using 120 grit (rhyno) stickon pads, buy quite a few cause your going to need them, also wear thick gloves because you thought these get hot on the grinder, its 5times worse on a bench wheel.
11, fitment Just line them up where you want them, i could only hold a few at a time, tape together as you go.
I bought mine to a fabricator to tack up, because i am no fabricator, i just decided to have a go.