When I put this project up, I specifically asked that anyone interested in it should ask for missing details.

It took less than a couple of hours for [paulvdh] to ask some questions.  I'll deal with the most pressing question first:

Yes, Bigfoot has a fuse.  I am well enough aware of my limitations as a hobbyist.  I know  that Bigfoot could at any time fail catastrophically, either due to a design error  (mine) or a construction error (again mine) or just because components do fail when you least expect it.

I've updated the schematic with the missing pull down resistors and the bleeder for the 300VDC supply.  I also added the C14 socket and fuse to make it clear that they are required.

The PCB is laid out to the best of my ability to separate high voltage from low voltage.

Bigfoot has two 12V power supplies.  One powers the Arduino, the tachometer, and the low voltage side of the isolated MOSFET driver.  The other 12V power supply powers the high voltage side of the isolated MOSFET driver.

Keeping things isolated like that means that I don't have to take any special care with the controls - they are all at low voltage and isolated from the mains voltage.

The housing is made of aluminum.  Since there's AC line voltage and 300VDC loose in there, I have the housing connected to the safety ground - the power cord is a three wire cord with a safety ground.

Typical sewing machine motors don't have a safety ground - that has always made me very nervous since the things have a metal housing connected to the metal housing of the sewing machine - and they run on line voltage.

I ran an extra ground wire to the motor on mine along side the 300VDC power output.

I've made Bigfoot as safe as I know how.

If you want to duplicate Bigfoot, please be sure that you know how to work with mains voltages safely.  There are tutorials out there on the internet.  Find some, read them.  Be very careful with Bigfoot's internals - it can kill you if you mess up.