We created an inexpensive, one-of-a-kind bathroom vanity by converting an old sideboard found at a resale shop. To save even more money, we used a secondhand sink and reclaimed marble tile to cover the vanity top.
Scour secondhand stores and estate sales to find an old dresser or sideboard that will fit your bathroom. Take into consideration the width, height and length of the piece. If it is too tall, you may be able to shorten it. Usually a minimum width of 18 inches is needed to fit a standard bathroom sink, but you're better off with a dresser that is 20 to 22 inches deep.
Cut out the center of top drawer in order to be able to fit the sink's plumbing. Plan to put the drawer back in so it will be stationary. Secure it in place with wood glue and nails from the inside so the drawer cannot be opened.
Use a drill with a hole-bit attachment to start the circle for the sink then finish cutting it with a jigsaw. Place the sink into the cut-out to make sure it fits (it is easier to cut more off than it is to fix a hole that is too big). Use a drill with a hole-bit attachment to make the cut-outs for faucet.
If you are laying tile down on the vanity top like we did, use a wet saw to cut the pieces. If you don't have capability of making the hole in the tile for the faucets (a tile core bit), cut half-moon shapes instead.
Dry fit all the pieces in place. Leave enough room around the edge for a trim border. Center all the pieces from the center line of the dresser. When all of the tile pieces are in the right location, label each tile to make it easier.
If you are leaving the top of the wood dresser as is, apply marine-grade varnish to the wood top to give it a protective seal.
One at a time, starting from the center, working outward, apply clear adhesive on the back of the tile and on the wood top (in a zigzag pattern) and place the tile on the wood. Wiggle each tile around to ensure it ise in the exact location you want. Then move onto the next tile, try not to bump the other out place but make sure they are pushed together at the seams (use a little clear adhesive there as well).
When the adhesive is dry, seal the top with shellac. Apply three coats. Make sure there aren't any gaps in the tile for the water to leak through.
Place sink into the hole, use clear adhesive to put it in place, then seal it with bathroom caulk. Double check there are no holes for water to leak through at tile and wood edges and seams.
Put the vanity in place and hook up the faucet (or call a plumber).