5/16"x 1 1/4" bolts and washers. Notice the hole in the middle of the carry plate - the "hand hold" holes. With another person on the other end, it's very easy to lift and move this boxed set of modules.
The carry plates are made from 3/8" poplar plywood that is used as flooring underlay for tile floors in the house. I find it has the same density as 1/4" fir plywood at half the cost but with that extra ply which provides added stability.
I regularly cruise the building supply stores and keep an eye open for sheets or pieces of plywood that are either in the cull bin, or have been damaged on the edges. I can usually pick up a 4'x 8' sheet of plywood for about $8-$10 and, once again, use their saw service to cut the sheet up into rectangular pieces.
I have the plywood cut up into pieces that are 25" long by about 18" wide. The width will depend on what kind of scenery and structures I'm going to put on the modules and whether I will have a backdrop. While the width of the modules is 24", I add an extra 1" to account for the thickness of two pieces of 3/16" Plexiglas or Luan backddrop and "finishing" washers that I use to fasten the Plexiglas/ backdrop to the module. This keeps the Plexiglas off of the floor/ carpet and reduces the amount of scratching when I load them into the car.
Poplar plywood can be a bit rough so I usually give each rectangle a good sanding on both sides and fill up any cracks with filler - body filler, wood filler, even spackling compound - anything that will hide those cracks.
The first step is to locate the middle of the plywood.
My next step is to locate the "hand holds" where I can insert my hand to lift the boxed set. After much experimentation with different sized holes, I settled on the following - simply two 1 1/2" holes (ie 3/4" radius) drilled into the plywood, the piece between the two holes cut out, and the edges rounded with a file. Here's the diagram for locating the two holes.
And drill the holes out using a 1 1/2" Forstner or spade bit.
Once I have the two holes drilled, I draw two lines between the holes.
In order to get my hacksaw (or sabre saw) blade right next to the edges of the circle, I file the edges square with a file.
Then, using a hacksaw blade or a sabre saw, I cut along the two lines between the two circles.
And here is what the final result looks like.
Since I'm buying a 4'x 8' sheet of plywood, I can usually get 6 carry plates out of one sheet which I then complete all at once (a bit of "mass production"). I next give the carry plates two coats of paint (pick your favourite colour). I'm now ready to drill 4 holes that match the location of the T-nuts for the carry plates. This we'll do later on.
For the moment, we're going to get ready to install the Styrofoam deck. As these steps are going to be quite different from anything we've done so far, we're going to do it one step at a time. So, before you race ahead, read all of the instructions first.