What a nice little project! You've made a very tidy start.
Cranks can be made from suitable brass strip (1mm thick?). Mark out the strip, then drill the axle holes, then the crankpin holes using a little jig (see first photo here), then cut out each individual crank. A pillar drill makes life easy, but with care a pin vice would do the job. For 2mm I'd use a 1.9mm drill and open the axle holes up with a 5 sided cutting broach, that way you can be sure of a good fit without worrying about the drill cutting oversize.
Here's some made for a Hunslet, and if you have a lathe life is even easier!