Agree 100% with Eddy thou I'm going to suggest you keep the size down to the minimum length you need because it gets quite a bit more involved building a good machine has the length increases and 2mtr+ machine I wouldn't recommend for a first time builder unless you either study in detail what's required for both design and components or seek advice from someone who's actually built a working machine at this length.!

Like Eddy suggests I wouldn't waste time or money on plans has everything you need is here on the forum and most plans I've ever seen have been crap and designed to be made from wood which is a recipe for disaster and disappointment.

Read some Threads then read again until you understand the pitfalls, post a build thread with what you have in mind and ask for advise on anything you don't understand.
Don't Rush in with building or buying components until your 100% sure they are the correct for your needs.