Sailsetc sell groovy mast, but I think that theirs is intended for larger boats. If you are making your own sails, it is quite reasonable to dispense with the idea of oval section and groovy, and just go with round and hitching the sail with rings, or, as I call them, bits of string.
Wood has excellent strength to weight, probably why it has been so popular for masts down the years. Dowel does a good job, just a question of picking the straightest length in the shop. If thin wall aluminium is wanted, K&S is good, but only comes in 12" lengths, so would need a joiner. Easy enough if the rig has stays and a spreader since the K&S tubing is sized to telescope.