These window shelves are surprisingly easy to make. They dress up a window and give you place to put knick knacks. I have made 10 of them over the years. The curtain rods for this one fit inside the side pieces.

On this one I saved the heart cutout from the side pieces and used them for the ends of an integral curtain rod.

This one uses a common closet pole to hang a quilt with.

My wife saw a picture in a craft magazine that she liked for the starting point. I laid out a 6 foot long piece of butcher paper, and starting drawing curves. I think I used dinner plates and jar lids to trace the different radii I used. Of course the layout must change depending on the width window you are making it for. I saved half of the top cutoff to use as a template for some of the others.
I used a jig saw to cut the top curves (its pretty long to balance on a bandsaw table), and hearts in the back. For the side pieces I use a bandsaw for the outside and a scroll saw for the heart cutout.

Here I am using an inflatable drum sander for the top curves. They cut much faster than solid rubber drum sanders. A spindle sander will also work well.

I put the parts together with wood screws, their is really no need to use glue. All screws are covered with wood plugs. More on that later. I use a round-over in the router on all parts except for edges that will fit flat against the wall.

Attach the back to the shelf first. Make sure you use clamps to hold the two pieces tight against one another when you drive the screws or the screws will actually hold the two pieces apart.

Before attaching the sides, make sure the back and shelf are flush, sand or trim if need be. Next make sure the back and shelf are square before attaching the sides. I use Rockler Clamp-It assembly squares. Lots of clamps to hold everything securely.

Now you can pre-drill the holes into the back and shelf, and then run in the screws. Note that the reference line on the side marks the top edge of the shelf so I know where to drill the holes.

You have a couple choices when plugging the holes over the screws. You could just cut off pieces of hardwood dowels. This will give you end grain which will be a lot darker than the surrounding wood – some people like that contrast, and even accentuate it by using a different wood species. Or you can save scraps from the cut offs and use a plug cutter to make plugs that exactly match. They are invisible is you take care to align the grain when you glue them in. Oh – by the way – I use 3/8 inch plugs.

And here we have it assembled. I usually use Watco Danish Oil Finish on mine. All mine have been made out of red oak, so I like to use the Watco Fruitwood shade to bring out the red in the oak. Or match the stain on the woodwork in your home.
I usually don’t drill any wall mounting holes till I know where it is going and can determine if I have a window header or wall studs to hang it from. If you keep the mounting holes within an inch of the top of the shelf they will be invisible to all but the very tallest of your guests.