Making the oneup bigger

[R2004]

How to expand it?

[LambdaFF]

Hi R2004. Theoritically speaking, it would not be too much of a hassle, at least for part of it :
- a longer bed to expand the Y axis
- longer rods for the Z axis
- a little tweaking in the soft to modify the parameter ranges.

In the end though you'll just end up with a narrow bed. So the real interest would be the X axis... but then you'd need to redo most of the frame and carriage system. In which case you're probably better off buying a bigger machine from the start. You're new here so I don't know how much of the above you can perform on your own. Improving a system while learning about it can be frustrating.
There are perfectly good reprap kits that are much bigger for reasonable prices. Unless you're technically inclined, try to learn with an already working machine, it's more fun.