Finally I took matters to to an end and got me a new laminator since the one I had before was /way/ too big for my new flat. It has two heated drums which is important to have an even heating and so prevent warping. Of course this does not prevent it altogether (2 materials) but it is way better than the one heated drum before.
The thing is called Peach PL713 but its not available on amazon right now (only the peach “photo”). So mybe you can find one just as cheaply at your local office supplies store. For Etching I use sodium persulfate With 100g per 500 ml (go metric! :D). Have fun and see you next time!