You can chose any size and any dimensions. We recommend a minimum of 2.5mm thickness and for larger medals the minimum should be 3mm for adequate strength and quality. Your medal can have cut outs, can be 3D, can be any colour. It gives you the opportunity to be as creative as you'd like to be.
As with size you can chose any shape. You can go with the traditional shapes such as round or square, but you really can have any shape. The sky is the limit. Think about what you'd like on the medal as this usually dictates the shape. Some shapes such as a star have less space than a square.
The bigger the medal; the more material is being used so they are more expensive. However if there is a large cut out in the centre, the weight is reduced and the price can be brought down.