Every time my niece comes over, she takes the cap of this one dimmer out and says “ooooops I accidently broke it”. Laughing.

And yes, it's broken. Every time I'm getting a bit more broken too, from inside, thinking “Why haven't I fixed it already?”

I made holes on the side so you can see the blinking light in the switch, helps finding the switch in the dark.

I really don't know the brand of the original part, the original cap is in the pictures. 

The inner diameter of the center hole is 6mm. Outer diameter of the whole part is 46mm. If you need one, go give it a try!

I just pushed it on it's place, it fits perfectly and firmly and I bet my niece will get dissapointed next time…

Can't imagine that anyone would need precisely this kind of part, but if someone does, that's cool!

Cheers!