Did you ever try assembling your cylinderheads with
an ondinary valve-spring compressor?
You always seem to need 3 hands to operate the tool, hold the cylinderhead
and remove the clips.
Usually this results in damaged parts and clips that fly through your
garage,
and land in the middle of a big pile of scrap-iron....
I solved this problem by building my own valve-spring compressor from
the same
pile of scrap iron, using amongst other things parts of an old vice-grip.
I can now compress the valve spring using one finger, go for a beer,
and then with a little magnet remove the clips!
I can also use this tool to measure "travel to coilbind" when installing
hot camshafts.
The whole thing costed me absolutely nothing to build and has worked
perfectly for the last 9 years.