This is a case designed to connect a HAKKO style T12 digital soldering iron controller to Milwaukee M18 batteries. I designed it all in FreeCAD, and made an attempt to style the case similar to other Milwaukee M18 devices. Veio with and without iron holder are included. Also STL files are included so that you can print your own. You can find an inexpeive controller kit for around $22 at https:www.amazon.com/gp/product/B07KNT9DXL/ref=ox_sc_act_image_5smid=A3KAKSP1F9N2ZH&psc=1.Updated files to fix a few erro, and to have a little better "click" when attached to the battery.Visit the HackADay.io project at https:hackaday.io/project/190764-milwaukee-m18-soldering-station.