do you have a particular iron you like to use with yours?
An iron that would probably work extremely well for you is made for
use on model airplane iron-on covering. The shoe is about four inches
long, by two inches wide, shaped similar to a laundry style iron,
Teflon coated and has a handle about a foot long. It is adjustable
for heat level, and able to get hot enough to melt plastic. They also
make little cloth socks that cover the shoe to prevent scuffing,
although they tend to interfere with the heat transfer and will burn
if left on at the highest temperature.
Do a search for “monokote iron”, or go to towerhobbies.com. There
are several manufacturers, but Top Flite makes the Monokote Iron, and
it’s the best, imo. You might find a used one, but I would recommend
a new one as a used one might be scuffed and have some of the
covering pigment left on it. They used to be about $30 but I haven’t
priced one in a few years.