Stopped at Home Depot on the way home and bought the hinged screw covers (3 for $0.85 inc. tax)
Think of your Chuck's button as having 3 levels:
1) silver hexagon that lies against the Chuck
2) skinny metal sleeve that rises from that and surrounds the button
3) the button
The #6 hinged screw cover is a zillionth of an inch too small to fit around the middle level. The person helping me said the next one would be too large and it would be better to drill this one a little larger. (Or, in my case, file it larger.)
Just got it home. The problem is that you're supposed to put the screw
through it, close it and never look at that unsightly screw head again. The only way I've found to open it is to shove a pen in from the bottom. So that's no good.
If you snap the cover off, it
might work by creating a little moat around the button -- kind of like
MickiO's solution but with space to push down with your finger.
Also, these covers are too shallow for a larger one (which would surround the hexagon.) In addition to covering up a lot of your customized design, if the cover were closed it would push the button itself.