Ground Hits
Using Compressed Air
Use seperate cans of air for each hit and seperate tubes. Pack plastic wrap with Fuller's earth or other light powder and heat seal. Conceal this under a light layer of sand. Fire off each hit by activating it's can.
If a weed-sprayer is not available,use a hot-water bottle.
Drill a hole in the screw-in cap, feed out a small piece of tubing, glue it in place, then slip plastic from a supermarket vegetable bag over the tip. Twist on some airline tubing, cut a small trench with a trowel and bury the tubing, and, at the "action" end, twist on an "L" shaped piece of tubing, and bury it a little below ground in a tiny pit (which will become the "bullet hole"). Set a small piece of stained balsa atop the "L", fairly tightly, and stack fuller's earth, tiny bits of shredded foam, and peat moss on top of the balsa.
When it's time for the hit, jump on the hot water bottle. The plastic ruptures, the blast of air kicks everything in the air, and it looks great.
Run a long hose from the compressed air container or air compressor underground. Cut a hole in the tube, and make sure it it visible. Put concrete mix or fuller's earth over the hole, then "let 'er rip."
Other Methods
It is possible to use a device which which simulated ground hits triggered by trip wires as the actor runs by, just by using wire and modified mouse traps.
Turn your mouse trap over and drill a hole where the bar would be after it is set off.
Use about 40mm of dowel.
Cock the mouse trap and tape it.
Put the dowl thruogh the hole and glue a piece of card to the top and bottom. This will stop the dowl from flying out when the spring is released.
Onto the place where the cheese goes, tie a piece of thread. When this thread is pulled the spring is released snaps overand pushes the dowl up. This action will throw your dirt up in the air.
Make a little box that the trap is the top of and bury it on location with a little dirt sprinkled on top.
Put a good bit on top of the dowl and tie the piece of thread to somthing accross the path of the action, and pull the thread.
You could screw 6 or so spring loaded rat traps to a piece of plywood. Set the traps so that the trigger is facing away from where you want the debris to go. CAREFULLY set the traps. Very gently, place the debris across the snap bars. Using fishing line, connect all of the triggers to a single line. Clear the area and pull on the main line. If you set it up right, all the traps should go off at once and throw the debris into the air.
Dig a hole in the ground about 3 inches deep, then take a long length of Fishline and the cut out bottom of a disposable plastic cup.
Poke a hole in the center of the plastic and run the fishline through and knot it so it won't come out.
Add some tape for security and then lay it in the bottom of the hole with the fishline running out of the frame.
Fill the hole with very dry dirt and remove any small objects. When the line pulls the plastic out quickly, you have a bullet hit.
