Summary

A divider thing to put inside a glass that you use to hold things.

Divide a glass into multiple segments to keep the toothbrushes from fighting, or keep your pencils organised, or whatever.
Select the size of the glass, the number of segments, the wall thickness, and chamfer if you want for the inside edge of the glass.
If you want a chamfer it is printed on the top of the print so there is no overhang.

Measure the inside diameter of your glass. If it tapers then you need to use the smallest diameter or convince me to make a tapered option.
Decide what clearance you want between the divider and the glass. If the glass is perfectly round this will make it all ok. I use 0.3.
Decide how many segments you want to divide your glass into.
Decide what wall thickness you want. I use 2.
Decide how tall you want the divider. It doesnt have to come up to the top of the glass, or it can go past the top of the glass if you want.
Decide if you want a chamfer. The bottom inside edge of the glass is rounded. You can add a chamfer to make the divide sit on the floor of the glass, or you can let it sit on the rounded corner. I think it looks better sitting flat on the bottom so i use a chamfer but i cant make your decisions for you.
If you do go with a chamfer (as you should) then you can decide how big you want the chamfer. The size is the height and width of the chamfer. The chamfer is put on the top of the divider so you are printing it upside down. That means that there is no overhang.