"True" wax build-up for models?

Re tip shape:

The tendency of molten wax to pull back from a point is a nuisance.
Many years ago the Giles Precision Waxer was recommended to me. Otto
Frei now calls it their Ottowaxer. (Unfortunately, I do not have
experience with comparable models.)

This unit has two kinds of tips, spatulas and pens. The pen has a
groove down its point which brings the wax into contact with your
work. I have modified mine, additionally, for a much finer point. I
fix a piece of 20 gauge silver wire to the pen tip. Sterling is soft
but it conducts heat well and can be soldered on to itself. I taper
the wire to a fine point and the curl a tiny loop at the end, as
tiny as I can manage. The wax does not pull back from the loop.

Re wax wires:

You can make molds to inject wax wires of various shapes and
diameters. The resultant wire will be flexible for a while. They
will be short. The difficulty is in finding an injection wax that is
not too gummy to finish easily.

Good luck, Jon Abbott

Jon,

I fix a piece of 20 gauge silver wire to the pen tip 

How exactly do you “fix” the wire to the pen tip?

Thanks, Marta