Ok, I agree, 1x8 and mt2 are better, but to be realistic, you can get almost everything I have seen or heard of used for pens in MT1, and 3/4x16, or you can use an adapter to 1x8 for the arbor. You probably won't find them used for a song, but you can get them. The only absolute limitation I know of is that if you want to use a collet chuck like a beall or a PSI, the adapter and the smaller mt opening behind it will severely limit the size of items that you can slide through the collet and secure for drilling and milling. The adapter will also almost inevitably add some runnout to any accessory it is used with. These do not absolutely preclude using them, just limit their application some.
So, in the long run, IF you end up needing some of the accessories used for more advanced penmaking projects, you will probably spend more than it would cost you upfront to buy more commonly used lathe. However, you can make plenty of pens in the meantime. If the less expensive lathe means that you can start making (and hopefully selling) pens now rather than later, then go for it, hopefully you can make the cash for the more expensive accessories by selling some pens. (that's the theory anyway)
So, don't let the limitations of a smaller lathe keep you from getting started, Just make sure you understand them upfront and are willing to live with them longterm, cause it's REALLY expensive to buy all the stuff for the small lathe, and THEN decide you can't live without a bigger one (and all the new tooling all over again) DAMHIKT!
