I just had a thought, I've not tried this. You might make these things without glass, using instead a block of wood that's drilled two ways, one horizontal in plane with the deck and two holes vertical 90 degrees to the deck to drill into the horizontal hole. Then just plug the extra holes with a glued in dowel piece. Coated inside with epoxy should work fine. You would then though end up with a square hole that will take a bit of playing to get lines through it but you could make most of it on a drill press and then just epoxy them into prepared holes in the deck.

Could do it a similar way using a round router bit to make a slot in a block of wood with no end holes and then drill into this slot thru the deck.

Bill H.