Quote Originally Posted by DrUsual View Post
Tinkercad only measures (easily) the OD of a circle, though, so I did 74 OD of the bottom + 3 mm lid walls = 77 inside diameter of the lid, plus clearance.
Ok, so this is the confusion. What do you mean by 3mm walls? If you mean the wall is 1.5mm then it would be 3mm total, but if the wall thickness is 3mm then the outside diameter must be the inside (74mm) plus the 2 x 3mm = 80mm outside dia for the lid (plus a bit of clearance of course).