Our new washer's drain pump was way too fast for our older plumbing, and was prone to making watery messes.  This gets installed at the back of the washer where the drain hose connects, and slows the drain flow just enough for my old plumbing to keep up.

I intended to upload this as a parametric model, but I've lost the (openscad) source.

I printed in petg, no supports needed.