A simple rotator for samples, modified from a version in the NIH 3D print repository. The mixer will gently rotate samples (speed determined by the motor installed), such as for HMW DNA extractions and Oxford Nanopore library prep. It runs on a single 9V battery, and is very simple to assemble (I have limited experience with building anything electrical and managed it). Total cost was around 40 USD, mostly the additional parts needed. Main supports are PETG rather than PLA since I work in colder environments, but PLA will likely work for all components. You will need a total of 4 of the fins, so make sure to print that plate twice!

The original version on NIH used a slightly different motor, and the one I used ended up being a bit bigger. As a result, I resized the motor battery cover to accommodate it.

Additional materials:

• A small motor, 12V DC geared. I used this one.
• 1/16" thick rubber sheet between the halves of the fins, and for feet.
• I-Type 9V battery connector
• A small extra bit of wire (3-5") to complete the circuit
• 9V battery
• Some electrical tape
• small rocker switch, such as this
• A roller bearing, external diameter 21 mm and internal diameter 8 mm
• 2 long screws and 4 nuts, 3/8" or 5/16".
• 4 O-rings, 9/16" OD 5/16" ID 1/8" thick
• 12 #2 flat phillips machine screws and nuts for paddle assembly
• 7 #4 flat phillips machine screws for motor mounting