I know what you're thinking, but hear me out!
The overall shape and size of this little trash can seemed "just right" for my application (meaning: minimal modification for lazy people like me). The 1/8" thick plastic is probably a little thin for optimal heat insulation, but it would be easier to cut and should be better than nothing (preliminary results posted further down). Rubbermaid claims this tough product will resist stains, chemicals, heat (not sure how much), and all kinds of abuse. In addition, the plastic is molded in black with nice rounded edges, so I wouldn't need to paint or refinish my heat shield when done. And who can't resist the price: $3.95! I figured: "Hey, if I screw up, I'll only be out $4, right?"
When I got home I placed the trash can on top of my intake to gauge exactly how much "modification" would be necessary to make my heat shield fit. After positioning the Rubbermaid in different orientations
, I found one way that I thought would work nicely: