Boxerworks.com

The wedges do have a triangular cross section, but one side is concave to match the curve of the bar. This curved part has lengthwise ridges to dig into the chrome, so I think lead would be too soft to do the job. A couple pics from Duanes website: I think the notch is clearance for the mounting bolt:

Jean wrote:l...even better if you finally find the one you dropped.

I strongly resemble that remark, Jean.

Tim to the rescue. Thanks for the excellent photos. I reckon lead would do the job, given that it is constrained within the triangular prism shape. Perhaps it would be worth gluing a bit of coarse abrasive paper to the base surface for extra grip.

The lead that wheel weights are made of is pretty hard.
I had to do a LOT of file-fiddle-fit to get the right shape. I DID know about the ridges, but didn't put so many in mine. hacksaw slots work.
The wedge in the picture looks a bit deformed at the clamp end...
Best not to lose the bleedin' thing.
wait till later for the beers.

2¢ on the subject of perch gear clamps.
My perch wedges are safely stored away, somewhere.
I prefer to have the clamps not so firmly tightened down.
As my motorcycles occasionally find themselves horizontal.
And for me, the common result of instances of motorcycles traveling horizontally vs vertically,
is damage to perch switches, levers and clamps.
I learned that allowing the clamps to move when impacted, greatly reduced the damages.
I like to stock spare levers,switches and clamps.
And for the boxer, extra valve covers.