Cardboard building blocks probably work just as well, and are probably considerably quicker! haha
Thanks for the words of caution, I will make sure I keep it in mind.
Thanks for reading!

I found these blocks years ago in a catalog — they are about the size of standard bricks, and look like brightly painted bricks once folded and tucked into their final shape. When I didn’t want to see the primary color, I just covered in fabric or paper of my choosing. They are only about an inch in depth, so don’t take up much room. If you’ve got it to spare within a cabinet, I highly recommend! They are lightweight but VERY strong.

Meanwhile, a note of caution — keep an eye on your vanity top in the coming months and years, as that annoying center piece isn’t just for show. The vanity top may start to sag, so subtlely you don’t notice until one day — Yikes! You might consider placing two vertical supports inside the cabinet such that they don’t block easy access to your storage bins. This came to mind as I just realized my elderly mom’s extended counter top on her bathroom sink/vanity wasn’t strong enough to maintain its horizontal integrity, and has sunk enough in the middle to make opening the drawer in the cabinet more and more challenging.

Thanks for sharing your stuff!