Yep it is...and extremely satisfying when you make one that works so I do that when I can, it is not usually about saving time or $$$ for me. I made my clutch tool from an ABS pipe cap and other stuff from the hardware store, though I can't recall what the thread was other than SAE (not metric)
(disregard the swarf from the window cuts, I got rid of that later and FWIW I also added a drilled steel strap across the top for strength)