Practice Box Details

At home we use this piece of equipment to do play training with puppies to accustom them to a box's operating sounds and 'feel'.  It's use in class is to teach tentative dogs the box is fun with an easy to use box.  It is designed with a gentle angle on the pedal so the dog need only step on it to trigger the box and so be rewarded quickly.  I keep it set so it will trigger easily and gently eject a ball, just rolling it out with minimal sound from the hammer.  As a dog gains more confidence we will prop it up in increments so the pedal angle is more and more acute to simulate the pedal angle on our other boxes.
In the picture above you can see a blue material between the matting covering the pedal and the pedal.  This is sleeping pad foam from CTC, a large sheet runs less than $20.  Thanks to our teammate Peter Perry for this feature. Dimensions:  Length 25 inches; width 11 inches; height at the back 11 inches; height at the front 5 inches.  The sides and base are made from a couple of scrap pieces of 1" X 12" pine.
In the picture top left you can see two lines of drywall screws running up the side of the box at an angle.  These secure the base plate and supports you can see in the picture at the right.  Note that the base board is also secured to the supports. 
Above, two L brackets hold the ball tube to the base board.  I use the brackets for a template and drill holes for bolts and bring them through from the inside.
Left, the face plate of the box is made of 0.5 inch plywood and secured with drywall screws.  The ball tube is a five inch length of 3.5 inch PVC.  The hammer material is maple, but any material that will hold together will do.  The hammer is padded to deaden the sound of the hammer strike.

 

Below, a good view of the trigger, a common door handle and latch.  The cost is low and the handle is easily replaced with a screwdriver. Below, the striker mechanism should be attached to the inside of the pedal before the pad and matting are put on. Below, the striker can be seen just resting on the release handle.  I carved a bit off the corner to give a better area of contact.
Two L brackets, a couple of eye bolts and a spring give the hammer it's pivot point and action.  The pedal stand off spring is set in a piece of 2" X 4" with a 1.5" X 0.5" spring held in place with a drywall screw.  The spring can be turned in or out by hand to adjust pedal release pressure.
Except for the hardware (approximate cost $30.00) this box was made from scrap wood and leftover material.  We have found it worth the cost and effort; even one dog learning from it would make it worthwhile.