How to extrude vertex along paths and odd angles or circles AT A SPECIFIC DISTANCE

how do I do something like this. ? gg xx so its extrude xx -.25 works but in only some cases.
will blender recognize this on a but some angles blender wont recognize. also I hope to be able to extrude a vertex along a path to a certain distance. Also how would one extrude along a A path or a mesh “circle” to a certain distance.

extrudeproblem.blend (607.1 KB)

The snap utility will snap a line to an edge but it wont let me specify a distance. I would have to create a vertex at the point I want to snap to.

I’d say use custom transforms. Ctrl-alt-space is the way to quickly set it, or just use the add new user transform which will be generated in relation to selected geometry.

However I’ve found custom transforms have some unaddressed bugs in 2.79b. Mainly to do with extrusion and repeated operations, unfortunately it switches to normal mode instead of respecting the user specified transform setting. Still works ok with rotating and moving though.

So extruding alone may be questionable. But you could define your custom transform, extrude from a vertex, snap it back to an earlier vertex, and then move along the custom transform. Not ideal in workflow (extra steps to get around the bug), but still workable.

Might try looking into 2.8, or perhaps a more experimental 2.79 build if 2.8 doesn’t run on your computer. (2.8 doesn’t run on mine, so I could only guess whether it has been fixed yet. Experimental builds tend to focus more on stuff like Cycles features, so I haven’t checked them lately either.)