I've added slots to each of the sinks that had enough space for objects to be placed on them.
In total I've edited 24 sinks (including base game and all packs). I've not added any swatches, they are all the original EA colours.

Some sinks aren't included because there wasn't enough space to put slots without it looking out of place, or that the objects were defying gravity. I also didn't touch the "kitchen" sinks as they snap into counters, which already has slots we can use.

The majority of the sinks have only 2 slots added, either side of the taps at the back, so you can place toothbrushes and soap. Or anything else you wish.
Where there was more space, I added more slots. A few of them have a shelf underneath the basin, so where there was empty space I added some extra slots for any other clutter.
Some of them had more space on the top so there was enough room to include 4 or maybe 6 slots on the back.

I'm always using the 9 and 0 keys with moveobjects to maneuver the toothbrushes and soap onto my sinks. So I thought I'd make it easier and add slots so it just snaps into place.

I haven't changed the location in the build/buy menu, or the price of any of the sinks. They are all found in plumbing > sinks

May conflict with other mods that edit the sinks listed below

This is an OVERRIDE it will REPLACE all the sinks I've added slots to

You can download the all in one file if you own all the packs.
You can "mix and match" the downloads by downloading the base game sinks + whatever packs you have installed separately (each are labelled for which pack you need)
The base game sinks are seperated if you don't own any packs at all



Edited sinks & number of slots:
Base Game
Brut Pedestal Sink (4 small), Bureau Sink (2 small), Cru Cabinet Sink (2 small), Poulton Footed Sink Vanity (2 small), RAW Pedestal Sink (7 small, 1 medium), The Amaranth (9 small, 1 medium), The Patrician (2 small)
Cats & Dogs
A Tastefully Sophisticated Sink (2 small)
Seasons
Ain't That A Slate Sink (4 small)
Get to Work
Gets the Job Done Commercial Metal Sink (2 small)
Get Famous
Mid-Century Wash Basin (5 small), Sumptuous Swan Sink (2 small)
City Living
Solent Sink (4 small)
Eco Lifestyle
Semi-Private WashUp (2 small), La Vatea Inc. Outdoor Sink (2 small, 1 medium)
Get Together
The Wash Basin (2 small)
Outdoor Retreat
All-purpose Pebbled Sink (4 small)
Vampires
Gothic Pedestal Sink (2 small)
Realm of Magic
Hera's Peacock Sink (2 small)
Jungle Adventure
Opulent Hand Carved Sink (2 small), Wide Basin Sink (2 small)
Parenthood
Single Pipe Sink with Wooden Cabinet (4 small)
Spa Day
The Water Falls Sink (6 small)
Laundry Day
Bai l'Est Galvanized Sink (2 small), DIY Sink (2 small)
Fitness
Blivet Basin (2 small)
Tiny Living
The Sinkz Bathroom Vanity (4 small)