I'm the odd man out as per usual.
I recently acquired one from the classifieds having watched Qorax using one and then exchanging a few emails about it with him. On a personal level, I really wish I had bought one far earlier on, it has made coil building so much easier for me that I actually enjoy doing it again. Health issues had begun to make even a simple coil considerably harder to make than it was before. One of the unhelpful symptoms is an increasing tremor in the fingers, wrists and forearms, which increases tenfold when I am concentrating on doing anything fiddly. This had reached the point where I was beginning to realise that my entire vaping was becoming in grave danger of having to potentially abandoning my beloved RTAs and switching to those hateful and expensive Ready Made jobs such as you use with Nautilus etc. This too, would have meant I'd have to cut back on my favourite Liquids as they have the capacity of killing these Ready Mades far too quickly. So if I am honest, things have been looking more than a bit dire.
Enter the Coil Master 521.
This device has changed everything. At last, a solid and reasonably weighty device that stays where I put it, holds everything perfectly still on the platform and makes the whole process so much easier for me. Using one of the cheap ft Mandrel Coiling Rods to wind the coil, then transferring that onto a Coilmaster Rod and sitting that between the positive and negative posts ...... and job done. I love the ability to check my ohms as I am building and adjust as necessary without having to get involved with taking things on and off different mods etc to do the testing, then being able to Test Fire, again, without having to move anything...... Tremendous.
OK, I do not vape at high wattage and invariably I seem to always end up with builds at between .8 up to 1.4 ohms depending on the Atty. So I cannot speak for those that require considerably higher power. But for MY purposes, it has been an absolute Life Saver.
Perhaps not the most vital piece of kit you'll ever buy under normal circumstances, but for my unique requirements, I couldn't build anymore without it.
Put it this way? I can build a Calix up from cleaned component parts, to finished and fully functioning in about 5 minutes or perhaps less. Without it to assist....... more like 15 to 20 minutes on a Good Day.