Box call Question?

[C W]

I have made a few pot calls for my friends and would like to make some box calls. I have seen two types, one is hollowed out of a solid block and other is made with thin side boards and end pieces. Which style makes the better call. I'm sure there are +'s and -'s for each. Any insight would be helpful. Also, thanks for all the help I have gained from the members of this forum.You are a asset to the turkey community.

Curt