I started a different way, first I read everything that I could find on IAP. I wasn't going to buy the extra expensive taps and dies until I had the fountain pen "mechanics" figured out. I already had a set of metric tap and dies. For everything except the nib holder I substituted the standard metric tap and dies.
As I was reading I kept notes on lengths, sizes etc., and converted that info to my set of taps and dies. I drew up my ideas with measurements etc., so that when I started I had my plan ready to go. I first turned the blanks round to fit my collet. I cut my lengths and did my drilling and tapping using my collet chuck. When it came to the triple start and specialty tap and dies, I used what I had. I did order a few of the nib holders etc., from Classic Nib, and that one tap.
I ruined a few blanks on the way, changed what others had to make it mine, and finally had what I wanted. It worked, it looked good and it was my design. I was till using single threaded caps, all I needed was the triple start stuff. I researched the selling points with past customers, who and how many were interested in fountain pens. That was a flop, very little interest. Not enough interest to justify the cost of the taps and dies. So I was stuck using kits or wasting money.
But I learned a lot, I do use the same tap and die technique to make seam rippers, just no triple start caps. You can also make toothpick holders with the same techniques. plus a few other things.
For the tooling, the tap holder, I made my own using scrap aluminum I had, the dies holder, I turned a piece of HDPE and drilled it etc., to make it. My collet chuck, I already had, I have both the Beall and PSI, save your money get the PSI. Get a quart of automatic transmission fluid, it works as a lubricant when cutting threads on acrylic. Also works for wet sanding acrylic.