Uses magnet set available on Amazon:

https://www.amazon.co.uk/Magnetpro-Pieces-Countersunk-Capsule-Magnets/dp/B08K39Q1DL/ref=sr_1_18_sspa?crid=DNKN89QHS9WL&keywords=large+magnets+strong&qid=1674928191&sprefix=%2Caps%2C58&sr=8-18-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9tdGY&psc=1

Just glue this part to the inside edge of the bath panel.