I very often build my own DIY devices, and a difficult part is to build a
squared hole for the the male AC Power connector: look at the attached photo.
View attachment 111803
Because the hole is rectangular, it is not possible to drill the hole as for a circular hole.
Do you know if a circular AC power connector exists on the market ??
Neutrik Powercon has been mentioned. There are others, but often very large and multipole, more than 3.
A radical alternative would be to use a round hole and fit the standard IEC connector and close up the "open" sections of the hole with 3D printed inserts.
Another radical alternative is USB-C.
Nowadays "chargers" with 20V/5A are readily available.
And 48V/5A is making it's debut (yup, 240VA of power from a 500g 13cm X 6.5cm X 3.5 cm power brick with GAN Fet's!).
It is easy for DIY to use MC33/34064A to create a wide range of voltages from the 20V rail.
A single MC33064 with 20V Input can produce almost any voltage up to around 30VA (minus losses), including 48V, +/- Rails of anything from +/- 5V to +/- 20V and even high voltages for Tubes using either transformers or voltage multiplier cascades.
Of course, more modern parts that switch at much higher frequencies and are SMD are available, but are difficult for DIY.
So I am recommending the positively ancient MC33064A. Use Panasonic (formerly Sanyo) Os-Con and LC filters to clean up switching noise.
This also pushes most electrical safety and agency compliance issues off board, into a replaceable commodity "Charger Brick".
Thor