I'm sitting here looking at my Deep-V rims and thinking blasphemous rational thoughts, again, without a whole lot of information. The rims are quite heavy. There are already some access holes in the rim for spoke installation. Why not carefully drill some more holes to trim off some weight? You could use one of those really strong rim strips like the plastic Michelin ones so that you wouldn't have a problems with blowing through. I'm sure it's been done. I'm also quire sure there are diminishing returns and increasing risks. Anybody ever do this?
I'm not saying I'm going to do it, I'm just wondering. There was another thread where the guy was thinking of trimming off the braking surface of his clinchers with vice-grips to make tubular rims and this post is sort of in that vein.