I don't think the plywood idea is necessary---and would mean having to hide the raw edge.

It would be helpful to know what tools you have available to do this, since a minimum of a saw of some kind, a router, a sander, and clamps will be necessary.

Using the extra flooring would work. You could even make an artistic layout using different lengths and pieces for the pattern. Basically, you would use enough pieces to be 55" long and 18" (or so) wide. That will allow for precise fitting to the ledge. You would just glue all the pieces together(using what are known as cauls to keep the whole thing flat). You can make acceptable cauls yourself.

Using solid wood will entail gluing pieces together as well. But, that means more tools(a planer to get all the pieces the same thickness) and some kind of indexing tool---biscuit joiner/dowel jig/spline to get the boards even. And a LOT more clamps.

Just buy a sheet of oak veneered plywood and a short roll of iron-on oak edge banding. Make a jig for drilling 32mm holes for shelving. Match stain of flooring. Finish with topcoat. Bob's your uncle!

Good planning is half the battle. If you want the front rounded off - and I'm assuming here you mean the corners rounded off, but I suppose you could also mean rounding off the front edge of the shelf - then it will have to protrude, as handymac suggests by a couple of inches perhaps. Do you want it to protrude?

If you do, then you have to see what widths your floorboards are and make sure that the outer board will have enough support in the event that someone leans or hangs on it. If the widths work out so that the outer board does not have enough support, then it may look best to trim down the width of the inner board, so you can still use a full width for the outer board.

Is there solid wood beneath the drywall on this ledge? You need to know how you are going to hold it down and hold the boards together. Handymac is suggesting glue. Me, I like to be able to take things like this apart so that it is easier to repaint the wall, so I would use screws - either round-head or oval-head brass screws, to make them a feature, or carefully countersunk flat-head screws. If there is not solid wood under the drywall... hmm, the ledge at least has to be framed so you could install 16" long pieces cross-wise instead of going length-wise. Or go length-wise, but make sure your inner and outer boards can be screwed.

If the shelf does not protrude, holding it down is less of an issue. Heck, it could just be sitting in there - given the profile of the opening, it would stay in well, and frankly, I think it would look odd if it did protrude from this framed opening (and I think I would like a square corner too). Think of the shelf as a giant cutting board. You could assemble it out of floorboards or other lumber and make it removable as a whole. (you have to be able to get the wider back part through the front opening of the space, on a diagonal - check that you can do this). I've never worked with floorboards, but I'm thinking you may not even have to attach them to each other if you pre-finish them and if the outermost board hooks behind the opening's framing. The outer board would hold all the others in.

Mac and I are both assuming your floorboards are solid wood, not laminate. If they're laminate (or if you use the boards cross-wise), you will need to conceal the edge as you would for plywood, either with iron-on edge banding as for RRMI's suggestion, or with purchased wood trim.

If using the flooring proves too complicated, then solid lumber is available in a variety of sizes, and you should be able to buy dimensions that would add up to 16" or whatever you want. Say, two 1x6s, which would be actually 5 and 1/2 wide, and two 1x3s, which would be 2 and 1/2. I'm sure you can also buy a board that is the full size, but it may not be as stable (staying flat), it may not be finished lumber... or not precisely the width you need. Again, if you need to add a fiddly piece to make the width right, fit it at the inside edge.

Cutting the pieces precisely to length (and width) will be tricky and in case you blow it (as I am always at risk of doing), you could plan to use corner moulding atop the ends or along the back to conceal any unevenness.

To give any more specific advice, we would have to know more about your tools and your woodworking skills.

Karin L
PS your photos don't show for me so I could only magnify the thumbnails.

My woodworking skills are minimal, but I need to start somewhere. At this point I don't have much to lose if I screw up the project because was planning to repaint the display area anyway, so if I cause any damage to drywall I can patch and paint. Ideally I was hoping to make the shelf removable so I could build it elsewhere and then slide into place.

I don't have a lot of tools mainly because I lived in apartments for the past 10 years, so I never had a need for large power tools. We've been in our house for about a year now, so whenever I come across a project that needs a tool, and it's a tool that I'll use again I go ahead and buy it, otherwise I try and borrow from a friend. I am planning to buy a circular saw this week, so I'll have it when I start this project.. I already have a hand saw and coping saw, a palm sander, power drills, and a whole slew of other non-power tools.

I pulled up the pictures from when the house was being frames and yes there is a solid piece of OSB beneath the drywall on the ledge, and it looks like the contractor was using it to hold his microwave during construction. I could easily screw the shelf down into the underlying plywood and then if I ever want to repaint, just unsrew and lift out.

The floorboards I have are solid unfinished red oak, and I have quite a bundle left over with full length boards. I�m not sure if I should save these in case we ever have to repair damaged sections of our hardwoods. I was thinking of using the plywood as a base layer so I could affix the boards to the plywood and then lay the shelf on top of the existing drywall.

I sketched up a 3d view of the display area in sketchup. The display case widens at the back, so when I build the shelf I'm going to make it so it slips into this area to keep it from sliding out. I also provided a view of the back side so you can see the profile. {{gwi:2099146}}From October 10, 2011

Here is what I was thinking on making the shelf look like. I think I would like it to protrude a bit to give a little extra detail to the display area.
{{gwi:2099147}}From October 10, 2011
{{gwi:2099148}}From October 10, 2011

I can see three options, all going with the floorboards or dimensional lumber. Warning: this is amateur to amateur! The governing principle here is that the 3-sided square cut you have shown is very tricky to measure and do. These ideas are ways to convert that to a two-sided cut plus a straight cut.

One, you use the plywood underlay to make a shelf with floorboards on top that fits INSIDE the opening, and then make the protruding piece a piece that you cut out of a floorboard that is wide enough to cover both the board edges and the plywood. Then you place that flat against the wall, perpendicular to the plane of the other boards. So it's a little higher than the floorboards are thick (or make it as high as you want for the look of a thicker board), and it hides the plywood. Your amount of protrusion then is the thickness of one board.

Two, you skip the plywood underlay and lay/attach the boards independently in the opening as if you were laying a floor. You arrange your widths (trim the inside piece) so that you have a joint right at the inside edge of the frame, and the last piece encompasses the frame part and the overhang.

Third, you do the plywood option, but extend the plywood to the edge of the shelf while stopping the boards at the inside edge of the frame, so you leave some plywood showing. You put that in, and then you cut and install the last floorboard. Because it will extend past the plywood, the plywood won't show from above.

You can do most of that with a circular saw, or even hand saw if you have to. Getting the cuts precise takes some practice, so probably good that you have extra boards on hand. It is really a pest to get a cut just a shade too long! That kind of error is best corrected on a chop-saw type of tool, at least for me.

The one task you don't seem equipped to do is cutting the floorboards to width, so making lengthwise cuts. I don't think there is any way to do this besides a table saw, a tool that is very useful but rather large, not to mention potentially dangerous. You can get smaller table-top versions but I don't know how well they perform. And I was just reading in Fine Woodworking on line that there is some new technology coming on the market that stops (or even destroys?) a blade if it hits flesh. Anyway, whatever you get, use with care!

For finishing, I think you would need to sand and finish the boards before installation, but you may need to finesse things once you have it all assembled in place.

Finally, since you are putting the board in from the diagonal (to get through the frame), it won't pay to be too precise with cutting it to the length of the opening. You need enough play to transition the board from diagonal to horizontal. The amount of play you need depends on the thickness - so you will need more play if you use the plywood, or rather, if the plywood extends the full length of the shelf, which it does not have to do. Even if you are using wood only, you could round off the bottom of one end, but that might be getting just a tad obsessive!

Karin L

What about a shelf like this?