There are also furniture pieces that are made to connect to each other. Some are obvious like peg boards, but things like sectional couches, too.

Then there are the myriad array of cabinet doors. And folks like heavy built-in cabinets, but Ikea ones are just fine. They typically have better hardware. But nobody wants to be the equivalent of an installer in software, it seems.

Since you said beds, consider getting the wrong size bed for a room. Or mismatched head and foot boards.