I found an aspen limb which had been broken off in a wind storm and decided to make some cups. I left the bark on the outside and the wood has a very pleasant scent. I have been drinking coffee out of one that I made and I like how the aspen scent comes through in every sip. I heard that using tung oil was best for wooden cups but after trying it I prefer to leave them natural. So far they have not shown any signs of cracking.