hi, i really want to make my first cc object that is not purely cosmetic. previously i've only done CAS stuff, but this time i want to make a gameplay object.

my idea is to make a new "chocolate" fountain, which is just for vampires to use, as it is a plasma fountain. i wanna make it only useable for vampires, and fill vampire thirst need, maybe give a moodlet. anyone have any tips on where i should start? any help is appreciated!

Good news, you can likely do all of this with tuning in Sims4Studio. The only limitation is finding existing objects that have some of those features to sample/learn from.

You'll want to start cloning the original chocolate fountain and checking what object tuning it's using. This will be listed in the Tuning tab.
Click customise, give it a new name or let use the generated one, then click OK and it will be added to the package.
You'll then have a unique copy of the fountain tuning that you can freely customise.

From there you'll want to familiarise yourself with what XML tuning can achieve from that point, I personally learned a lot from Zero's XML Tutorials but there are quite a few good ones out there.
Use the TDESC Browser ( https://tdesc.lot51.cc/ ) or the Tools > Extract Tuning option to look at existing tuning- like if you know of objects that already have some of those features, look at them and figure out what part of the XML is applying that functionality.
You'll likely encounter a bunch of other types of tuning files like Loot, Buff, etc referenced in the first one. If you want to change what they're doing, add those to the package too and rename/renumber. So on so forth.
You can also open similar mods in S4S to see how they did it, what files they used, etc