When my Father-in-Law passed away in 1999 one of the things I inherited was his 80lb anvil. Being the professional procrastinator, I cobbled together this piece of art from 2x4's Promising to build a better one later.
I finally got off my duff when I came across some 1" plywood with black laminate on both sides.
I miter cut 4 identical sides, added biscuits glued it together (you can't see them in the pictures) but there are angle iron brackets inside at top and bottom corners to strengthen the miter joints.
At my age I don't want to being lifting anvils, I've been hanging on to these 4" casters for several years,
I cut the end off and drilled another mounting hole
I mounted the wheels about ¼" above the base so that it sets flat on the floor but when you tilt it back the wheels lift it off the ground and it rolls free.
I very happy with the way it turned out.