I wanted to get a Lego Minifig display case for my kids but... they are EXPENSIVE! So after looking around online at shadowbox versions (also expensive), I was perusing for pieces in Michaels when I came across this circular slatted board. I grabbed two, and some E6000 cement and ran home to get started!

"Consumables"

Circular slatted board ($6.99)
E-6000 ($2.99)
16 2x4 bricks (priceless)
Okay, maybe that's a touch melodramatic. But some of these blue ones come from my own 1980's spaces sets when I was a kid though... so maybe not too far fetched. Still, these shouldn't be too hard to find around your house if you're needing to house minifigs!

Tools

Metal ruler
Pencil
Marker

Step 1: Lay Out the "grid"

I lucked out. As you can see in the picture, my metal ruler was exactly the width of the 2x4 brick! Also, I opted to arrange the bricks so that no two bricks were directly above another (i.e. they're staggered). So here's what I did...

Lay the ruler down the center of the circle as shown in the picture.
Use pencil to mark just the bottom edge of each slat at the width of the ruler on each side.
Now add "columns" to each side of the ruler all the way to each side of the circle.
Use the marker to make small x's in the spaces where you'll glue your 2x4 bricks.

Step 2: Place the Bricks

Once the grid is laid out, start at the top row.

Squeeze a generous bead of E6000 onto the back of a brick. I used a generous bead because this is going onto wood and I want it to fill in the grooves and expect some of it to be soaked into the wood.
Place the brick onto the marked space and press down a little.
Continue placing the rest of the bricks.
Allow to dry 24-72 hours.

Step 3: Change the Hanging Hardware

These circular boards come pre-hung so that the slats hang vertically. So I simply removed the twine hanger and used some picture hanging wire on the back.