Dimensions
They fall into four rough groups: 5 smallest, 4 a bit bigger, 8 medium and then 5 in the biggest group.
I’ve put one of each group next to the wooden egg in the photo below - it is the size of a standard hen’s egg.
Heights - the smallest is 5.5cm, the tallest 11.75cm. Most are around 8-10cm.
Diameter at widest point - around 4.25-5.5cm
Opening - around 1.25-3cm