Jar lid 4 thread

Jar lid to fit (out of the box), 100mm (4 inch) diameter jar neck which has four 180 degree screw threads at 30mm (1 1/4 ") pitch or scale or rebuild to your requirement.

Supplied with the Blender pre-assembly file as a simple "learn Blender" project for you! To adapt the lid to your requirements, install Blender 3.80 (or later) and open the jar_lid_pre_join.blend file.
Select View | Front (or number [1] key on keypad).
The top object is the cutting tool comprising a 51.5mm diameter cylinder and 12 intersecting torus arcs for threads.

1. If required, adjust the torus arcs to your desired thread position and pitch
2. Mouse-click to select the Cylinder. In the tool window at the bottom-right select Modifiers | Add Modifier | Boolean. Select Torus 000 as the Object in the Modifier. Click [Apply] (see screen-shot). This will cut the shape of Torus 000 into the Cylinder.
3. Select Torus000 in the object tree (top-right), then right-click it and select Delete. This will reveal the thread cut-out in the Cylinder. Repeat steps 2. and 3. for Torus 001 to Torus 011 to cut all the threds.
4. Select the lid, (Cylinder 001) and drag it upwards using the blue arrow to almost cover the cutting tool (Cylinder). You should have about 1mm of the cutting tool visible above the lid which will be the thickness of the top of the lid.
5. With Cylinder 001 selected, add a boolean modifier and select Cylinder as the modifier Object. Click [Apply] then delete Cylinder. This will cut the threads into the lid.
6. Select the sealing ring (Torus) and drag it up so that the bottom of the Torus is fractionally above the bottom of Cylinder. With the Torus selected, shift-click the lid so that both objects are selected. Right-click and select Join.
7. You should now have just one object left - your finished lid! Drag it around using your mouse with the middle button (wheel) pressed to check that it looks as expected (see screen shot).
8. Export as a STL file (or your preferred format) for slicing.