There are two rules
- Multi-colour stamps must have a minimum of 2.5mm between each colour.
- Any one colour must be at least 7 x 7mm
A different colour border is also not possible generally unless you have a huge space around the perimeter. This can be achieved with a larger body of stamp than the image you require.
See the rest of the Trodat multi-colour stamp range here
Choose from 16 colours of Trodat ink, see them here