Imho you should have bought and assembled a kit and have a good working printer before you set off on making your own for several reasons. First off you will have a good model to look at to get an idea of all the pieces and parts needed to make such a thing. Second you will already have the experience of assembling a known good model so you will know what to be chasing when you try to create your own. You will also find that having a working printer to design and make parts for your creation also really helps out. I think it is a wild and crazy idea to say that you have never had a 3d printer and have no experience with a 3d printer and you are just going to step up and build one. Don't you? I mean when you read this it has to sound a little ambitious, no?

If you want to build your own the start with something like this: http://www.ebay.com/itm/2017-Latest-....c100505.m3226

Assemble it, and by the time you work out all the bugs and have a decent printing machine you should have a good idea of the parts you would want to use in building your own 3d printer from scratch. But right now the 3d printer that you would build surely would be less that the cheap ebay kit in performance and most probably for more money.