That looks really good man! What settings did you use to cut yours? And material type?
I have used wood, plastic, and aluminum for stamps so far. I would recommend a very tight-grained wood and hard plastic if you go that route. I have a modified machine, so my settings will not really be useful for you. You should use the best settings for the material on your machine. I will say that the more detail you cram into a smaller space the lower angle V-Bit you are going to want to be able to produce that detail. I think the one I showed above came out OK with a 60-degree V-Bit.