i've lose the battery cover for my flexfit remote for a long time. still functionaly as a remote, and I tend to use my phone to control my bed anyway, but it annoys me for not having the battery cover, so I measured the dimensions and remodeled the cover

if you want to print this, make sure you print with PETG, as it requires small pieces to be somewhat flexible in order to fit, and my attempts with PLA all ended up with failures (the locking part snaps inside the remote)

also make sure you do NOT print this belly-up, as it will rely solely on layer adhesion to hold the latch part in place, which will tend to fail if you use it over and over.