Metaprobe environmental DNA passive sampler (based on original design by Giulia Maiello and the Stefano lab). Design has been revised so hexagon flow cutouts are rotated 90 degrees to reduce the need for supports/bridging.

The metaprobe is a 3D printable hollow, perforated, spherical probe that can be used as a vessel for membranes in an aqueous environmental sample. A) The shut metaprobe. B) The shut metaprobe with three FloppE-Dip membranes zip-tied. C) The open metaprobe; one-half with two zip-tied FloppE-Dip membranes, and the other with one zip-tied FloppE-Dip membrane.

For printing parameters, we recommend printing at as fine of layer height as you can (~0.1 mm layer height is fine) and with 100% rectilinear infill. You should be able to print these as-is without supports, but you may need a brim depending on your bed adhesion. Afterwards, it would be good to sand the outer surface that may have some imperfections due to overhangs and then lightly heat the outside with a heat gun or blow dryer to smooth out the surface and better anneal the layers (careful not to overheat and deform the ball shape).

Regarding method refinement, we’ve opted to attach three nitrocellulose membranes to the inside of the balls  instead of using filters or the gauze balls used by the Stefano lab. These can then just be preserved in silica gel beads instead of the high volumes of ethanol required by the Stefano method. We’ve had great success with this method so far and are currently putting a paper together to showcase the results.