1. You cannot make consistent pots if you do not weigh your clay16 oz and 18 oz will yield very different results. If you pug your clay, measuring the pug is a quicker alternative.
2. Lids that fit come from consistent measuring. Make lids to a specific size and make fixed gauges for each size lid you use. It's easy and cheap. Here is the most simple gauge you can make. It costs nothing to make and gives results as accurate as you will ever need. Use it for the lid and the seat and you will be happy with the results.
Here is the deluxe version for those of you who must have a caliper. Just one nail at each end. Use as an inside/outside caliper and it will leave you a tiny bit of wiggle room.
I know lots of people who throw to a "needle" Usually this involves setting up a mound of clay next to the splash pan, doing some not too accurate measuring and sticking a knitting needle through the lump of clay followed by more adjusting. Here is an easier way. A board with a hole in it stays clamped to the table. PVC pipe drops into hole. skewer of your choosing goes through horizontal hole in pvc and is fixed in place with a drop of silicone caulk. Make a different post for each size pot you make multiples of. If the post wiggles, wrap the butt of it with tape until it doesn't wiggle.
That's it kids. I've got a show next week ( Yellow Springs Ohio Aug.8) so I need to get busy in the studio. Hope these tips save you some time and effort. Thanks for stopping by.