I'm just starting on the same shield method with a Flexible Flyer sled (26"), and I was hoping you could answer a couple of questions. First, how did you take care of the lip around the edge? Second, what did you do about the handle holes? Thanks!
For the lip on the sled I took a double bladed saw since those cut smoother with minimal kickback and cut it off. Then for any rough edges I took it to a bench grinder and evened it out. For the holes I did two things. My first few shields I used bondo with a small cutout of sheet metal as the backing. But it looks bad and doesn't always hold up. So I started cutting below the holes and removing them all together, which actually gave my shield a better dimension, took away some of the curvature at the edges that didn't look right.