1. Buy some Mullins 35mm trees and ebay some forks. Add to frame and congratulate yourself on having great taste when it comes to narrow front-ends.
2. Apply ruler between forks. Accompany ruler round swapmeets, scrouge ebay, wrangle advice until realisation that the only drum your ruler vaguely approves of is from a cub 50 scooter which has an axle diameter of about 6.734 mm.
3. Decide: brakes or suspension. Or machine your own hub but by that time you've already laced a Kempton found drum to the Borrani rim even though you knew it wouldn't fit but it was a twin leading shoe and you got carried away. Brakes over suspension it is.
Chop (all important word) the fork tubes.
This is actually the first part I ever made on a lathe.
Milling in the lathe.
At this point I drilled and reamed a hole. Actually I snapped the pilot drill half way but seeing as it took me like two days making this part and working out how to use the lathe, I alternated. Plunged an end-mill in about 2mm (the snapped drill bit rising into the hole in the end-mill), oxy-acetylened it, hammered protruding drill bit flat, plunged the end-mill another 2mm, repeat 10 times until mad with the world then enlarge messy hole to correct size.
Make a little axle.
Trim the fork tube caps.
OPTIONAL: Advise all comfort cynics that you spent everyday for the last four years riding a completely rigid bicycle with 19mm cross-section tubular tyres at 180psi around crappy, pot-holed, English roads and you only had to see the doctor about an embarrassing lump on your anus once. This should distract them from knowing best about vibration damage, cornering-grip, and other borings.