The Missouri Department of Natural Resources describes a Machine Shop business as:

A machine shop is a room, building or company where machinists use machine tools and cutting tools to make parts.

You may need some or all of the following permits for a Machine Shop business:

Hazardous and Solid Waste Amendments Part 2 Permit https://oembed-dnr.mo.gov/waste-recycling/hazardous-solid-waste-amendments-part-2-permit

Waste and Recycling

This is one of two possible permits that make up a hazardous waste permit. A Hazardous and Solid Waste Amendments Part 2 Permit contains the federal hazardous waste management regulations administered by EPA that Missouri has either not adopted or has adopted but EPA has not yet given Missouri temporary or final authorization to administer. This "Part 2" permit is issued by EPA, if warranted. EPA does not issue a Part 2 Permit if EPA has no site-specific conditions for that particular facility. Please visit the Hazardous Waste Permit.
Hazardous Waste/ Infectious Waste Transporter License https://oembed-dnr.mo.gov/waste-recycling/business-industry/permits-licenses-registrations/hazardous-waste-infectious-waste-transporter

Waste and Recycling

If you or your business plans to transport used oil, hazardous waste (combustible liquids, corrosives, poisons/ toxins, flammable liquids, flammable solids, PCB's) or infectious waste in Missouri, you are required to obtain a Hazardous Waste Transporter License.

Even though the request is approved by both Missouri Department of Transportation (MoDOT) and the Missouri Department of Natural Resources, you must apply for and renew the license through MoDOT. For more information, please visit MoDOT's Hazardous Waste Transport webpage.
Missouri Hazardous Waste Management Facility Part 1 Permit https://oembed-dnr.mo.gov/waste-recycling/missouri-hazardous-waste-management-facility-part-1-permit

Waste and Recycling

This is one of two possible permits that make up a hazardous waste permit. A Missouri Hazardous Waste Management Facility Part 1 Permit contains the federal hazardous waste management regulations Missouri adopted and EPA authorized Missouri to administer. This "Part 1" permit is issued by the Missouri Department of Natural Resources to all facilities obtaining a hazardous waste permit. Please go to Hazardous Waste Permit.