There's a few different designs out there for magnetic stir plates usually based around PC fans. I really wanted a stir plate that could stir at both low and high speeds and was simple to construct and safe to use.

The unit cost for one stir plate is $9.50 for the electronics. Everything is printed in PLA with 20% infill and no need for supports.

Assembly is pretty straight forward hook the power jack up to the PWM controller where it says DC in and the 12V motor to the PWM controller where it says motor.

The power jack and 12V motor are hot glued in place and M3 screws are used to secure the lid to the base.

Here's the part links (I have only tested the Amazon parts linked, but since the Alibaba parts should be cheaper I would love to hear about if anyone uses them):

12V motor

Amazon(tested): [https://www.amazon.com/gp/product/B07CJNXTV1/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B07CJNXTV1/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1)

Alibaba(untested):

[https://www.alibaba.com/product-detail/High-torque-low-speed-rpm-carbon_62139089260.html?spm=a2700.galleryofferlist.normal_offer.d_title.4b46635byn7NAe](https://www.alibaba.com/product-detail/High-torque-low-speed-rpm-carbon_62139089260.html?spm=a2700.galleryofferlist.normal_offer.d_title.4b46635byn7NAe)

PWM speed controller

Amazon(tested):

[https://www.amazon.com/gp/product/B07GP72BWV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B07GP72BWV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)

Alibaba(untested):

[https://www.alibaba.com/product-detail/Mini-DC-DC-4-5V-35V_1600868356590.html?spm=a2700.galleryofferlist.normal_offer.d_title.a7e4294bB8da0R&s=p](https://www.alibaba.com/product-detail/Mini-DC-DC-4-5V-35V_1600868356590.html?spm=a2700.galleryofferlist.normal_offer.d_title.a7e4294bB8da0R&s=p)

12V 1 A power supply

Amazon(tested):

[https://www.amazon.com/gp/product/B082D7W362/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1](https://www.amazon.com/gp/product/B082D7W362/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1)

Alibaba(untested):

[https://www.alibaba.com/product-detail/6V-9V-12V-15V-18V-0_1600835786939.html?spm=a2700.galleryofferlist.normal_offer.d_title.5aae13c1AdCISb](https://www.alibaba.com/product-detail/6V-9V-12V-15V-18V-0_1600835786939.html?spm=a2700.galleryofferlist.normal_offer.d_title.5aae13c1AdCISb)

Magnets

Amazon(tested):

[https://www.amazon.com/gp/product/B09QHS6VSJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B09QHS6VSJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)

Alibaba(untested):

[https://www.alibaba.com/product-detail/Cylinder-5Mmx3mm-Magnets-Iman-De-Neodimio_1600608478356.html?spm=a2700.details.0.0.1d9934b4WM3FTb](https://www.alibaba.com/product-detail/Cylinder-5Mmx3mm-Magnets-Iman-De-Neodimio_1600608478356.html?spm=a2700.details.0.0.1d9934b4WM3FTb)

you'll also need 3mm x 10 mm screws and some 20 gauge electrical wiring. If you need to purchase that here's part links:

20 gauge wire

[https://www.amazon.com/gp/product/B08CC1DLQF/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1](https://www.amazon.com/gp/product/B08CC1DLQF/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1)

M3 screws

[https://www.amazon.com/gp/product/B0B51BFSWZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1](https://www.amazon.com/gp/product/B0B51BFSWZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)