In the dim past, this question was explored on Orchid. The
responder’s name escapes me, but here is the answer given:
Purchase a common strap hinge with equal, triangular sides, some
wood screws, a domed carriage bolt (with the raised letters filed off
and polished smooth), and another polished carriage bolt with nut.
Mount one side of the hinge on a sturdy piece of wood (like a 2x4)
and drill through the end screw hole so that you can screw in the
domed bolt. On the free side of the hinge, in the matching end,
insert the domed bolt and secure with its nut. It may be necessary to
cut the bolt shorter if you use a long bolt.
The two polished carriage bolts should meet, dome to dome, as mirror
images. Place your metal between the bolts and hammer on the nut.
Both sides of the metal will be hammered. If your wood base is
clamped to your bench, you can hold the metal and shift it around
between the bolts while hammering. In time it will be necessary to
repolish the bolts, but that’s easy.
I hope the description makes sense. If not, feel free to email me
off line and I can send you a photo.
Judy in Kansas