Coffee Appreciation

what are the ones with a convex base like? can't really stretch to a reg barber one so it will be one of the espresso gear ones.
it's going to be used with a cubika

Isn't convex vs flat base a matter of preference? So I'd heard anyway.

Would be interested if you find a place to get a tamper as I need a new one and would like to buy somewhere in town if possible.