Plyo Box

A friend recently had me build some wooden boxes for his crossfit workouts.  Crossfit is a fitness program where you do a variety of movements that exercise multiple muscles at once within a short amount of time.  When used as part of a crossfit regimen, ordinary wooden boxes become plyometric or “plyo” boxes, that provide an intense workout.  How do you use them? You jump on them to develop strength, speed and explosiveness.

He had me build 2 large boxes (measuring 30-inches x 24-inches x 20 inches), and one smaller box for his daughter (20-inches x 16-inches x 12-inches).  The different sizes of each box’s sides provide three different heights to jump on.

Plan

I determined to build the boxes from 3/4″ high-grade hardwood plywood.  I would router out a 3/8″ x 3/8″ notch on all 4 inside edges of each side.  These notches would allow each side to be overlapped to the adjacent side making the joints stronger from both directions.  Notching the edges would also allow for more glue surface area at each joint (also adding strength).  Here’s a sketch of a large box with the top and bottom removed to show the notched edges forming the joints:

Here’s a diagram showing the actual dimensions of each side of a large box that accounts for the 3/8″ notch and overlapped joints so that the finished box ends up exactly 30″ x 24″ x 20″.

For the smaller 20x16x12 plyo box you need:
(2) 19-1/4” x 16”
(2) 19-1/4” x 11-1/4”
(2) 16” x 12”

Procedure

I started by cutting all the plyo box sides from 3/4″ birch plywood using my table saw.  To help me make the cuts I made a make-shift support for the heavy sheets of plywood using the coffin I made for Halloween a few years back, an old piece of laminate countertop, and some other scraps I had around.  Pretty ghetto I know, but it got the job done helping make the cuts as accurate as possible.

Once all the sides were cut out, I routered the inside edges of each piece.  This required two 3/16″ deep by 3/8″ passes with my router.  Having a router table really helps with this step.

Here’s a shot of the notched edges after the first pass:

After the second pass through the router, I used a hole saw to drill a couple holes in one side of each box.  Then I used a jigsaw to remove the plywood in between the two holes to form the box “handle” or “grip”.  I used a round-over router bit to remove the sharp edges of the handle.  Then I sanded these smooth.

Then I laid out the sides of the box on the floor and put some wood glue on all the notched edges:

I used some straps and some finish nails to hold the boxes tightly together until the glue dried:

Next, I used my router with my round-over bit to smooth off all the outside edges of the boxes. (Otherwise, I imagine you could get a fairly nasty cut on your shin by slipping off during a workout).

These boxes don’t really have to be that pretty, but I went ahead and puttied the nail holes and any minor voids in the joints with natural wood filler.  Then I sanded all the boxes smooth.

My friend used a stencil to spray paint numbers on each side showing its height:

Demo

Of course I figured you’d want to see a little footage of how these boxes are used…

DIY Material Cost Breakdown for 1 Large Box:

  • 4′ x 8′ x 3/4″ birch plywood $48
  • wood glue $5
  • finish nails $2
  • natural wood filler $5
  • sand paper $4

TOTAL $64

24 Replies to Plyo Box

  1. Mark in PA says:

    Smart move to notch both edges. You make it look so easy!

  2. Lee B says:

    Why didn’t you use screws instead of nails? Just curious.

  3. Jon G says:

    Thanks for posting this plan. Great website. You do nice work!

  4. Stephen says:

    Your finished product was/is beautiful. You kicked it up a notch. Totally grateful that you posted the plans dimensions. I’ll be following suit. Thanks.

  5. Joe says:

    Awesome, gonna try this. Just one question.. You only need one sheet of wood for all three boxes?

    • Joe- If I remember right I used a little over two sheets to make the three boxes. If you’re just making one box- one sheet would be enough. Also, I remember trying to figure out how to cut out the pieces leaving the least amount of waste since the sheets of high-grade plywood are a little pricey.

  6. Ervin says:

    Hi Kurt, I’m looking to make a box myself by following your instructions. I’m new to woodworking and do not have a router. What kind of ‘beginner-intermediate’ router do you recommend to be able to accomplish this task?

    Thanks in advance
    Ervin

    • The router I have is a Craftsman brand my wife bought for me as a present. I think she got it from Sears. It’s nothing fancy, but the small router table it came with is very nice to have, and it works well for the small projects I use it for. She gave me an assortment of about 8 different bits. But if you don’t have a router, you could just sand down the edges of the box so they’re not as pointy and sharp.

  7. Charles Furer says:

    Thanks for posting this project. I especially appreciate how you use everyday solutions in the build, like your coffin stand and strap clamps: the kinds of solutions this NYC backyard DIY’er needs and relates to. “Shop” is wherever I lay my saw. I’m going to build a half dozen of these boxes for some make-shift seating in my yard for barbeques, knowing I can stack them in the corner when not in use. Of course, I’ll be using screws, because the elements will compromise the glue, and I’m going to put some kind of varnish on them for protection. Nice, simple design, reminiscent of the apple boxes we use on film sets. Sort of the Brutalist school of design, one of my favorite looks. Take care.

  8. Rob says:

    The part about “two passes through the router”…..is the finished rabbit 3/8in by 3/8in? Or 3/16 deep by 3/4 wide? It appears to be the latter based off the pic. Also, did you the do the rabbit on all sides of all six pieces?

    Thanks for the how-to.
    -Rob

  9. Bas says:

    Did you use a 3/8 bit and then set the router at 3/16 deep? or a 3/16 bit at 3/8 deep?

  10. Jimbo says:

    Good looking boxes. About what did you spent for each box in materials? I’ve been shopping around the internet to see what the price difference would be. Well done on yours.

  11. Kristy says:

    I want to make one of the smaller boxes. Can I get it cut at the hardware store? Then I can put together myself. What do you estimate the cost of a smaller box? Thanks!

    • Go for it Kristy! Hardware stores can sometimes help you cut the material, but I don’t think they’d router the edges for you. One sheet of plywood should easily be enough for one small box. Last time I checked a sheet of high-grade 3/4″ birch plywood was about $48.

  12. Justin Reno says:

    Thank you so much for the DIY bro.. cuts went well routed out the edges and everything went together easily.. Wish more things I attempted were this way… It was all due to your detailed instructions!! Thanks Again.. any other DIY gym stuff you got in mind?

  13. Ray says:

    First best instruct-able site I have seen to date. Great job with it.

    Quick Question: I am a bigger guy: 6’3″ 230, and work out with a buddy that is 270+. If I use your design, is there any concern regarding weight?

    I am all about over engineering for safety. If I wanted to add some internal support just in case, how would you recommend I do that?

    Thanks!

  14. Lara says:

    Hi,

    I was wondering what size router would work? Would a 1/4 router work?

    Also, do you have the dimensions for the small box?

    These are great!

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