Paul,
After making a wooden prototype first, I used aluminium plate to make a fixed angle (38 deg) wedge for an 8" Meade. The base was 19 mm, the angled plate 10 mm and the gussets were 12 mm. It was very stiff and served well for visual observing for a few years; it's not used any more so I guess that I should unload it. Some pictures attached, plus a link to my construction thread, where the wedge can be seen with the LX90 attached in post #12
http://www.iceinspace.com.au/forum/s...ad.php?t=36222
The base is about 325 mm square, and the angled plate is about 250W x 270H - comfortably fitting the 8" SCT at the time.
Cheers, Chris