Printed them with semi transparent PLA. The very first one in the direction of the STL File. I happened to have some ugly overhangs and printed a second one vertically angled. The second one came in "superior" quality. They both sound extremly nice though. I wonder how you keep producing such consistent and nice results with blender as i always run into non-manifold errors with more than 2 boolean modifiers. Which version are you running?