Because of space constraints I've designed compact shampoo bottle holders so as to minimize risk of bumping into them.

The two shampoo bottle holders will hold most regular type bottles, one for oval shaped bottles, the other for round ones.
I've added some drawings with the main dimensions.

The oval type I've printed with some supports at places of severe overhang.
With the round type Ive used 3 outer walls for some added rigidity.

They both attach to the wall with 2 regular 4mm screws, plenty strong.

Remark: as always, the stereo images are of the cross-eyed type.