This batch, I’m making some plastic lids for my jars with a syringe filter for air exchange and a rubber stopper as an injection port.
For the lid itself, I purchased the “regular size” lids, which as the description on Amazon says, fit both the half pint and pint jars I have. I came to find out jar lids are standardized to a 2.75″ regular size and wide mouth being being 3.375″, and so I chose regular.
I also decided to use a 13mm diameter syringe filter so it wouldn’t take up the entire lid, trying to keep a good space between the stopper and filter. This became helpful when drilling later.
For the holes, I used a Ryobi drill bit set. After some measuring, the hole I used for the syringe filter was 5/32 and the hole for the stopper was 5/16. The biggest problem was cracks, though and I had to be very careful and DO NOT PUSH DOWN HARD WHEN DRILLING. Let the drill bit do its work and have patience. Pressing too hard OR putting the two holes too close together will cause cracks, making the lid useless.
I tested size and drilling first on a piece of cardboard, making sure the stopper and filter fit nicely and then made a template for the lid, using it to drill my first lid and then used that lid and a pencil to mark the drill spots on all the rest.