This thing is meant for studio photography. If you already own flash modifiers which are using the bowens mount you can use it to connect them to continous light sources (like LED corn cob lights) using a simple E27 socket. The foot is for a standard 16 mm spigot connection (common standard for studio light stands).

If you want to make one of yourself you will need:

12 brass inserts for M3 screws (4mm pilot bore)
6 metric screws M3 x 7 mm
6 metric screws M3 x 12mm
1 metric nut M8
1 metric wing screw M8 x 25 mm (or longer)
1 corn cob LED light (E27 socket)
1 lamp socket (E27) with cable and switch and clamping ring ( 40 mm diameter)

Hole covers need to be printed 3 x.

!!! Attention - use at you own risk - ensure that the heat generated by the bulb is not melting the holder or igniting the fabric, with LED lights I myself did not encounter any significant heat buildup, but you need to check and ensure safety yourself for your given combination.

Anycubic

All-metal Mega

No

Yes

0,2

40%

Print laying flat on the bed, use supports to get good dimensionally fits, where the three connectors snap in place. If turning the speed ring needs to much effort you can reduce tension by taking of a little of the prone area of the holecovers.

Insert the 12 brass inserts on the back of the backplate (using a soldering iron)
Use the 6 shorter M3 screws to fit the covers.

Fit the longer M3 screws through the holes of the "Stativanschluß" make sure that every screw has found its counterpart before fastening all the way.

Insert M8 nut in the hole for the light stand connection, Use Wing nut to keep in place.

Put socket through center hole - fix with clamping ring.

Et voila