extrusion models from jpeg drawings

[magicniner]

The first thing to understand is that there are two distinct image types, a "bitmap" is made up of dots, if you zoom in angled lines and curves become jagged, in a "vector" drawing you are always viewing the software's interpretation of a description of lines and curves, when you zoom in the software re-interprets the object description at the current view size, curves and angled lines stay smooth.

When converting bitmap images you will need to create any information you don't have, this means that ideally a bitmap image you wish to work from should look good when viewed at actual size or larger.
If when viewed at actual size your bitmap has jagged edges any software that you ask to "trace" it will follow the jagged edges and that's what you'll get in your "vector" drawing, (CAD drawings are "vector" drawings) so to trace it and get a good outline you'd need to spend a few hours in a bitmap image manipulation package to increase the resolution and smooth out the jagged edges.

If you have a good clean high resolution bitmap image of your part in straight black and white with no dimension lines or other noise there are software packages like Adobe Illustrator and Corel Draw which have a "trace" function which will give you vector outline of your bitmap image.

The quickest way to get the image you have posted here into CAD is to draw it as it's a very simple repetitive pattern and drawing it will ensure it is accurate as dimensioned,

- Nick