My Vendetta 1.5 has an aluminium seat. I was really sore at the top of my sacrum after a 40km time trial attempt the other day, and noticed that there is a bulging weld line which may have been the trouble. I've slipped a strip of closed cell foam and small rectangle of 3cm thick open cell foam inside the cruzbike cover, and that has made a big difference. I think the hard line of the weld was impacting on the bone through the original padding.
Slim's discovery of the drainage matting is a good one! It may be possible to get it even cheaper from civil engineering suppliers in your local area, as it's used behind retaining walls to ensure drainage (and therefore reduce pressure on the wall). The quantities used in drainage applications are usually many meters. Such suppliers might even be a few offcuts laying around that you could get for free.
I have a computerized knitting machine. It can knit pretty much any 1 bit (i.e. two colour - B/W) image - with a few limits on large blocks of single colour. Lots of small areas of alternating colour are better. Anyone keen for a custom design cushion cover in whatever yarn, wool, acrylic, silk/blend, etc? I guess Larry needs something to match those "billboard" wheels of his?
Pixel size is not square, stiches are more like 1.4times wider than they are high. Stitch sizes about 2mm wide by 1.4 high typical 3-4ply.