Inspired by PaulB's Mandarin Feeder design, I just made a 3D print version of it. It started almost 2 weeks ago from the drawing board, literally:
Sep 18th: I like to have the tube removable and leave the feeder on the sand bed and let the fish keep picking on it.
A small connector that always connected to the long plastic tube for pouring the shrimps in. It can then twist onto the base feeder that is sitting on the sand bed. The feeder could have an optional even bigger sand bed base that go under the sand so the feeder won't get blown around by the water current. There will be a cap for the feeder. Either just direct 3D print with tiny holes, or an open cap to allow using a normal mesh.
Sep 25th: After many days and many re-design for real world issues, here is the latest design:
The feeder is anchored down by the base to avoid floating away or getting blown around by the reef tank water current. Just a push and a twist on the feeding tube, and the feeder can be removed from the under-sand-anchor:
After pouring in the BBS, you can unscrew the feeding tube from the feeder. The rigid air tube is compression fitted to the screw-like connector. You can put in a blind-plug to close the hole without getting your hand wet.

The screw-like connector is loosely fitted until the last turn.
Here is the under-sand-base and the feeder:
Everything is modular design. If you have a thinner/thicker air-tube, just need to re-print the screw-like compression connector. If you have a different size funnel, just re-print the funnel-airtube connector.
The screens are changeable as well.
The next revision is work-in-progress to have interchangable under-sand mounting legs, so that it could be buried in various places and situations.