Model A. Door Handle Adapter: slips on to sliding door handle.
Model B. Magnet Halves: superglue 5x3mm magnets, then hotglue non-wire half to sliding door frame.
Model C. 6x Sections: join together with 1mm wire, then join to ends with 1mm wire.

Magnet retention breaks, with no damage, if door opens too wide. The segments attach to each other, and the ends, with 1mm steel wire. The wire pushes in easily, 2cm sections at a time, with needle nose pliers. The smaller/inner section pieces, with two parallel holes, flip every other piece, alternate bed side and top side.

Parts required for one complete accordion baffle:

• 18x 5x3mm rare earth magnets, $6: https://www.amazon.com/dp/B09GLWMN7N
• Many lengths of 19ga/1mm steel wire, used as hinge pins, $4: https://a.co/d/bymtkwZ