And just to confirm, I did try to get another smaller cup cut into the 39mm opening but the only DIY shop I know in my area refused. They had drill head that needs to enter into the material in the middle and that would hold the head straight as it goes in for the big hole. Not sure hot to explain. Since my cup already had the hole in it, they refused to just make it bigger as they couldn't guarantee it being centered. It's a home center type of shop where they mostly deal with wood.
Anyways, the above solution seems to work!
Ben
Anyways, the above solution seems to work!
Ben