Following a few guides on the internet on modelling vacu-form kits, the first steps I took was using a black marker and draw it around the parts in an 45° angle. I tried to mark 50% of both, the actual parts and the styrene sheet around it.
I then used scissors and hobby knife to cut out the parts. I tried not cut too close to the parts before they have been freed of the styrene sheet left overs around it. Next step will be cutting them out very closely using my hobby knife and then the sanding process will kick off.