My custom paper (N)overlay (and how to improve it?)

Hello all, for my CataRT performance instrument, I use a quadratic area of the morph without overlay (since the magnets are not strong enough to hold one in place when doing expressive gestures), and two control strips for up to 4 fingers for modulation and other trigger modes. It worked quite well to separate them with a paper overlay (with a little fold in between the two strips):

However, after a year of use, the paper is worn out, producing ghost touches, and starts to tear apart (see below). The advantage of being able to put marks on the paper is actually moot since I’m playing this without looking anyway, so I wonder what better alternatives there would be to separate the 2 strips haptically? Two sticky threads/very thin tape? Should not leave a residue, ever, of course…

Thanks for your insight, cheers! Diemo
(music made with the Morph: