I need an electrical lighting designer

I’m designing and casting a sconce but I’m stuck on some technical details that are making the lamp ugly. I don’t know enough about junction boxes and lamp holders and how to work with them.

I’m using a Tala porcelain 3 bulb. And casting a half sphere form around it. Trying to figure out if sockets can be buried inside a junction box and if junction boxes has to be 10cm or if I could find smaller. The trunk is currently 72mm and is meant to have a machined plastic 1cm thick ring around the socket that attaches to the bowl through 2 set screws. I don’t know if this is the best design or a lamp holder with a screw cap could hold the sconce in place from the outside, without the plastic ring and set screws