I am working on a project that requires moving a 100mm long and <.5mm diameter pin a specific distance in a straight line. I want to move the pin in and out as fast as possible and accurate to less than .05 mm. The device needs to be as small as possible. The stepper linear actuators on the market appeared to be a good option but they look too slow and expensive. I was looking into using the electromagnet from a speaker, but I am not sure how to calculate the speed and accuracy of the push/pull. Any advice would be helpful. Thanks.