I did similar by hand on my Bell MX9 MIPs. I used a tea spoon and lots of force. Wasn't the best job. Ive got a Dremel but I don't have the Flexi shaft so not sure it'll fit in my helmet easily. Looks like a nice clean job. 👍
I'd think you could do it without a dremel. At least with other foam like in equipment cases and such you can put cross hatch cuts creating a bunch of little squares that are easily pulled out.
They would be pressing too much against the ears. So very little tolerance between the side. But that could also be me having big ears hahahah Cheers and thank for the feedback which. Also makes a good point and option too ! Rob
