Upgrade 2x2 growth series myself

[bryantar74]

I am wondering if anyone has upgraded their growth series themselves since torchmate no longer does it.
I would like to go from a 2x2 to a 2x4 or better yet a 4x8. I don’t know about exactly what I need and if the parts can be bought. Building the table looks fairly straightforward but the parts to make it work look a bit more difficult.
Any advise or ideas would be great.
Thanks