If the wheel has 12mm internal diameter cartridge bearings both sides, you can use Surly Fixxer parts, no custom fabrication needed.
From the pictures here and from what looks like the same one here that seems to be the case.
Presumably I wouldn't be able to use the actual threads on the Fixxer, and would still need something to screw onto the freewheel thread on the hub?
@tbc started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
From the pictures here and from what looks like the same one here that seems to be the case.
Presumably I wouldn't be able to use the actual threads on the Fixxer, and would still need something to screw onto the freewheel thread on the hub?