Just something to consider - you can buy one size pen and get different size tips as the are removable and interchanable. I asked Art Primo when they would get the 1mm pen in stock and customer service told me about the tips. A pair of 1mm tips is $2.99.
Although one can get them in resin, these were rebuilt UCT originals. The Unreal Edsel funny car or the pre-rebuilt UCT was probably the first model I built. The Edsel is being rebuilt. I hope to post my Bugs Buggy in a few weeks.