Bonding Metal Headbadge To Bare Metal Frame

[My_Teenage_Self]

Decent industrial double sided tape.

I'd also use Numberplate tape, but it's a bit thicker, and would space the badge from the frame a little.

 

[bren]

I'd go with the adaldite/epoxy suggestions myself.

Whatever you do just don't use silicon. It's acidic and will damage the steel and any excess won't be overpaintable.