Floating Puck This Thing is a simple, hollow, cylindrical puck which fits inside my [Water Level Sensor Housing]() to provide the Sharp Infrared Distance Sensor with a solid, matte black surface to reflect off of. It has an outer diameter of 44mm, giving it 2mm of clearance on all sides within the 48mm (inner diameter) Water Level Sensor Housing. Preparation ABS plastic (and possibly PLA plastic, as well) tends to degrade and "leach" into water, so it is advisable to thoroughly coat the entire part in some sort of sealant. I used Clear Shellac Spray since I had it lying around the house anyways, and it has the benefit of being non-toxic and natural Lac resin-based (a type of insect resin), which is used to coat food products, and should avoid issues of contamination in a sensitive environment (like an aquarium or food-contact setting) when used in room temperature or lower water-based liquids. An acrylic coating may be preferable in situations where chemical contamination of any kind is unacceptable.Design Like all of my parts, I used Autodesk Fusion 360 CAD software, UP slicer program, and an UP Mini printer. In Fusion, I sketched a circle, extruded it upwards, then shelled it, added a top, and joined all components. Printing For 3D printing settings, it doesn't matter which infill settings you use, other than 90-100%, which might prevent the puck from floating. hollow shell settings will work, as will (up to) 90% infill. Support structures are not needed, since there is no overhang in this Thing. A raft IS recommended to ensure a good base shape free from distortion.