Installing the ark bottom
I put the my 1/2" MDF bottom 1/4" up from the bottom edge of the box just to give myself a finger hold when lifting the box after it's finished. There are other options you may want to use on yours. If you put a bottom in it, and if you are sending it for any of the spray on chrome methods, you'll have to seal the all the joints with either epoxy or caulk. More on that later.
In the bottom view photo below, notice the 2" square 1/4" thick piece of MDF in the corner? That is there to provide a place to seal off the top of the leg for the Cosmichome process. It also provides a handy spacer to hold up your bottom 1/4" above the bottom edge of the box. I just glued mine in flush inside the bottom of the box before I placed the bottom in. I also used another 1/4" piece as a gauge to make sure the middle of the bottom board was also 1/4" up from the edge.
On the outside of the box, draw a line where the middle of your bottom board is so you can have a guide to nail it in from the outside of the box, around the perimeter. I didn't glue it in, because later you will add some inside corner pieces that are less messy to glue.
Due to an over-abundance of caution for the leg attachment process, I also recommend adding an inside corner block that allows you to put 6 more screws into the leg. I do this because while the leg is pretty strong, the part you attach to is the thinnest part of it.
Because I want the screws to go right into the corner, the easiest corner bracket to make is by taking a 2 x 4 and cutting a 45 degree bevel on one side. It will need to be 15-5/8" minus your bottom thickness and minus any hold-back you have from the edge to the bottom. In mine it's 14-7/8" long, though because it's more accurate, I'd generally cut this a 1/2" too long and mark the length precisely and trim to that, rather than cut to a measured length. You want the top to be as flush as possible with the top of the box. Note Note I happened to have the corner brackets I used made up from another project, so the one in the photo is a little more complicated than a simple triangle.
Once you have them cut to length, be sure and mark them so you know which corner they were cut for. Use the other acrylic template to mark the locations of the 6 holes for more of the #12 screws, though this time they will need to be 3"" long. The top is marked and you'll reference from there.
Get your drill ready to drill through the block into the corner of the box and leg. Use the same drill size as you used for the legs. Also have your driver ready to run the screws in. You'll use a lot of power to run these in and twisting out the leg isn't likely to happen since you are also going through your panel plywood.
Put your Titebond III on the corner block and put it in place. Drill through your holes and run your screws in. Be sure the top of your block is flush with the top edges of the box and leg each time.
philip