Right, so to single-wall my echo rim i used: 4" angle grinder with thin metal cutting disc ( 2-4mm ) flat file coarse sand paper ( 100 grit ~ ) fine sandpaper ( 200 grit ~ ) Put the wheel in a pair of forks/frame; now get someone to hold he opposite side of the wheel and to help turn it. Start cutting on one side of the inner skin, make a half depth cut all the way around the wheel on one side, then do the other side half-way through as well. Make the final cut on the first side all the way through the skin, i made around 8 diagonal cuts across the skin so the inner wall came out as several pieces, not just one continous strip. Now cut all the way through on the second side. Finish up by removing any large protrusions with the grinder. Note: Care must be taken not to hit the small lump near the braking surface, its a hollow structure, that is quite important to strucural integrity. the rough cut rim now has to be de-burred with the file, using long strokes and concentrating on any really rough areas, go around the whole room removing scurf until its all fairly even, and you can run a piece of tiolet/tissue paper around the cut edge without it snagging. I then finished it off with the heavy grade sand paper to give a clean finish , then used the fine grade to get it pretty much completely smooth. A reasonable amount of skill with a grinder is needed, along with a fair bit of patience.From start to finish this took me around 45mins for a front dual wall echo 07 rim. That wheel has been ruin for around 7 months with no punctures as yet. Any more help needed, just PM me...im singlewalling another echo rim quite soon so im sure i can help To save weight....and remove unnecesscary material. Also saves a fair whack of money compared to buying one of the new fancy Hole rims.