With a tea light cup in plastic it´s easy to create a perfect hole in any mould you want!
I prefer to fasten them inside the mould with double-sided tape, to keep it firmly in place. Or use hot glue.
It´s up to you if the moulds are reuseable. Smear a bit of oil on when it´s fastened, use warm water and patience when removing the mould:)
Inside measurement: Ø 42 mm
Height: 19 mm