How much you trim down from the top of the box depends on how big the box is to begin with. Use your best judgement. You can even use a milk carton. Cut out one of the side panels, then trim the walls down so that they aren’t so tall.
If you don’t have brown construction paper, you can use brown cardstock or even a brown paper bag. You can cover the bottom of the box, or you can leave it blank. It won’t be visible in the end. You can paint the box brown with acrylic craft paint, as long as it does not have a waxy coating on it, like a milk carton.
Miniature craft sticks with straight ends will work the best. If you are using the larger “popsicle” type sticks, cut off the rounded ends first. Enough space along the bottom edge so that you can poke holes for the axles. The space should be the same thickness as your dowels.
If you don’t have thin dowels, use straws or skewers instead. If your wagon is very small, you can even use lollipop sticks!
Paint the back of the circles for a nicer finish.
Hot glue or tacky glue will work well for gluing the yarn to the circles. If you are using hot glue, work 1 line at a time, or it will set too fast.
Make sure that the spokes are on the outside. The wheels must be centered. If you need to, draw an X across the back of each wheel to find the center.
A small box will require 2 strips. A larger box will need 3 to 4 strips for more support. You can use pipe cleaners instead of cardstock or cardboard strips. Cut the pipe cleaners if they are too long. Connect multiple pipe cleaners if your box is very big.
You can use tacky glue for this step, but you will need to secure the strips with clothespins until the glue dries. If your wagon is very large, add a third arch right in the middle of the wagon.
You can also use white printer paper or construction paper to make the cover.
If you secured the edges of the canvas to the wagon with tape, remove the tape as soon as the glue dries. If you used pipe cleaners, you can apply the glue to them straight from the bottle. You can also try hot glue, but work quickly so it doesn’t harden.