I built a log splitter for my backhoe with 1/2" steel plate. A local steel yard cut the pieces for me, so All I had to do was weld it together. I remove the bucket and use the bucket curl cylinder to push the ram.
It works quite well, and has enough power for pretty much everything that I have tried to split.
To make it operable by one person, I rigged up a rope and pulley system that lets me operate the valve from the splitter end.