The dial protector comes in three parts:

1. The lid
2. The base
3. The spring

The spring sits inside the base (as shown) to ensure the dial is held securely and cannot rattle around, the lid then has a small cone to center the dial and energise the spring. The dial is placed face up on the spring, the centre hole of the dial should be manually roughly aligned with the hole on the spring, when the lid is put in place and the cone will center the dial and hold the dial in place. The back of the dial is supported on the soft spring material which stops it from moving.

I printed the lid from clear PETG on 100% fill - but the effect was less than clear, maybe you will have better luck. No reason you couldn't use PLA/PLA+ for the same part. If you don't care about it being clear you could print with a colour at 20% fill.

I printed the base in white PETG on 20% fill. No reason you couldn't use PLA/PLA+ for the same part.

I used TPU 87A for the spring on 100% fill, but I think TPU 95A would also be fine.

Note: that there is a small gap between the lid and base, this is there to make sure that the lid bottoms out first to ensure that the spring is energised and the dial is held securely.

Good luck