Stain and finish your wood. First, smooth the board’s surfaces and edges with sandpaper and then clean away any sawdust. Then apply stain to match the color of your bathroom’s other wooden features, if desired. Once it dries, add a coat of wood finish (or, to make things simpler, use an all-in-one stain and finish mix to eliminate a step).
Skip the stain if you want to, but definitely seal the wood with a finish to protect it from moisture. Steam from your bath may warp unprotected wood over time. Use a rag or brush to apply either one. When you do, brush or rub with the board’s grain, not against it. Allow the stain to dry overnight before adding finish. Do the same after adding the finish before proceeding to the next step.
Wear protective gloves when using stains and finishes. Also, use a drop cloth or similar material to protect surfaces in your work area. Add handles. Attach handles to the top of the tray, if desired, for easy transport. Use cupboard pulls or any other type of handle that suits your taste. Follow their directions for installation, since each type of hardware may have its own specific instructions.
However, bear in mind: Cupboards pulls as well as other forms of handles may require you to screw through the bottom of the tray, rather than the top. If so, expect the screw heads to project out of the bottom once they are screwed in. Even if you use flatheads, this may result in the screw heads scratching the rim of your tub.
To avoid this, create a pilot hole by attaching a countersink bit to your screw gun. This will cut both a pilot hole for the screw as well as a slight divot in the wood’s surface that will fit the screw head. Attach grippers. Minimize the chance of your tray slipping off the tub’s rim due to moisture and anything else that may make it slippery, like bath oils.