I’ve created a fully-functional washer and dryer (Laundry Day required) based off the modern ones from The Sims 3: Ambitions. They are not exactly identical, as they are slightly shorter, both the washer and dryer are front-loaders and the drum looks the same as the Laundry Day machines rather than The Sims 3 ones. You can tell the washer and dryer apart from the drum and also from the top part with the buttons (the first one in the image is the washer and the second one is the dryer). I didn’t change the animation, so sims won’t really use those buttons on the top, but I did change the display symbols to the top part and they actually light up. Since the buttons are on the top, the dryer cannot be stacked on top of the washer.
The washer costs §800 and the dryer costs §825 and they both come in 13 color swatches as seen below: