Holy moly! No pressure. Let me diffuse some of the expectations: it's not going to be perfect!
Spent some time working on the leading edges this evening. Got them nicely trimmed and started on the finishing work.
I did make one fairly big mistake overall: When I initially trimmed the edges, it opened up the cardboard sandwich to the elements. With the amount of rain we've had, the cardboard has wicked in some moisture. The result is a couple of spots are noticeably softer. The corrugation has gone mushy.
Not that this thing was ever going to be
terribly strong - it would not survive a goat walking on it.
People: just use a piece of ABS when you make yours!