How far is the panamorph lens mounted from the projector lens? I need to build a hushbox and I want to make sure my dimensions are large enough for both to fit.
I think the short answer is that the anamorphic lens is mounted "as close as possible" to the projector lens. I haven't permanently installed my lens yet and it's not a Panamorph but it is probably less than a quarter inch away from the projector lens. If you are building a hushbox and figuring dimensions then I would probably lay your projector and Panamorph end to end, measure that and add 1" for wiggle room and then whatever you might need at the rear for cable connections. If your cables come in on the side of the projector then add extra space to the width for the bend in those instead.
Assuming you don't have the lens handy to measure it "as close as possible"... My U480 on the Panamorph/Chief mounting plate and sled protrudes 9" from the front face of the PJ at its deepest.
If you're building a hushbox, give yourself some extra room on all sides so when it comes time to upgrade you're as likely to get stuck for something that fits... (although projectors will probably continue to shrink in average size - though probably not as much as they have in the past)