No problem. Let’s start at the beginning.
You want a Credenza to hold a turntable and play that through some built in speakers. This is what used to be termed a Console (insert further descriptives here). By the time they fell out of favor, they usually had multiple ways to play music, and sometimes television.
Generally they had a FM stereo /AM broadcast section, power amplifier section, some sort of moving media such as a turntable/reel to reel/8 track/cassette, or a combination thereof. And they more or less had either 2-way or 3-way speaker systems built into the ends.
Turntable. Do you have one or will you be buying one? If you are buying one, there are many that have a Phono Preamp built in, which you will need if the rest of the system will be analogue (will be connected with RCA cables or 1/8″ stereo cords).
BlueTooth. There are many different (and very inexpensive) ways to add this.
You will need a regular preamp section where you can make input selections and volume/tone controls. Plus, this is where you will connect up all your media playing devices, including the 1/8″ jack.
At least a stereo amplifier. Believe it or not, most consoles of the day had between 10-20 watts with not very good distortion figures. You have many options these days. There are little Class D amps that can do 30-50 watts for as little as $10+-.
Speakers – many options here. Best left to when you get an idea of how big the end “boxes/cabinets” will be. You can then figure an internal volume to help select the drivers needed to work best.
The overall cabinet – that’s your baby. Come up with whatever strikes your fancy and make it real.
Anyone else have any suggestions?