This was done with Alexa Routines but there are similar features on Google Home (Routines) and HomeKit (Shortcuts).
A large prerequisite to this is the presence of SmartPlugs to handle the power on for your machines.
I’ve got an older post on smart plug, you can check it out, here:
http://arcadeshenanigans.com/blog/2018/2/13/smart-plugs-a-year-later
The obvious downside to the smart plug approach used here is expensive and network population, having 36 Wemo plugs means 36 IP addresses to allocate, 36 Netbios names to configure, if Siri integration is wanted, 36 HomeKit setups to complete. Wemo plugs can have setup and support frustrations, as do their competitors.
One incidental upshot to this approach is that it is a solve for the breaker instant-load issue you might get from flipping a physical master switch. If you flip a giant red ghostbusters containment unit looking power handle, electricity is flowing out at nearly the speed of light, in an instant. That could be a lot of load to introduce on a breaker panel all at once.
By comparison, each cloud-connected smart switch is going to take at least 120ms of roundtrip network traffic before it closes the circuit and passes power. Everything isn’t turning on at once. It seems like it is but the delay is enough to provide a curve to the load application.
Anyway… Been spending some time in the evening during the quarantine getting the games squared away and making tweaks to the automation. The Alexa routines provided a nice way to move management of the plugs away from the Wemo Rules engine and into the Alexa voice services where we are already pretty well invested as a household.
Stay safe, be smart, don’t trust everything you read.. oh and um… thanks for reading. :)