Those who have Edimun V3 might have noticed that it comes with customized red foam with 4 smaller holes. That gives it more or less a donut foam quality (that won't over-dampen treble) but without the downside of a looser fit which tends to make dunut foam falls out easily. While donut foam can be a life saver for certain earbuds from time to time, it isn't particularly suitable for MX500 style front cover (VE's, BugGuy's, etc) as this kind of cover don't have any sound vents near the center, but located closer to the outer edge - so they still get somewhat over dampened even with donut foam. Inspired by the Edimun V3 foam pad, I did some modification of my own to create the multi-holes foam pad that will work better with MX500 style earbuds. The holes are located closer to the edge and thus will expose some sound vents for more treble. It also has the upside of getting a tighter fit than donut foam. I won't say it is the perfect solution for every earbuds, but it does work better than donut foam on many occasion.
Get yourself a leather belt hole puncher and punch the foam away - you won't actually punch a hole with the puncher, but it will leave a mark on the foam that you can tear away with your fingers easily. Push the foam slightly inward when punching and the hole will be closer to the edge - but don't get too close to the edge though, as you will want to leave around 3~4mm of space.
Three to four holes are usually easier to do and three is my usual choice. Here is how they look compared to the foam on Edimun V3 (*in red)