Removing/deleting hidden lines after applying a clipping mask - for laser cutter or plotter applications

Thanks for that, I was able to use the shape builder tool on simpler masks, leaving me with 'fully cut out' lines in that shape. However with complex masks it just hangs and is way too complex.

I had mild success by making my likes into objects by expanding them, then cropping the mask using the Path Finder - however then for every single line it produces two lines (the outline of the 'line shape') - which is not the desired result.

Have looked around all the forums now and seems there isn't any simple way to 'flatten' a mask and make permanent what you see on the screen.

Surely lots of people want to do this for laser cutting etc?

Seems so simple but is missing.