The use of tamper resistant techniques in real estate radon inspections is often required. Here's how to build an inexpensive cage that looks and works great. This cage does not rely on electricity or batteries.
48" sump pump basin with lid (get it at a plumbing supply house).
5 open speaker grills (get them at Radio Shack or stereo store).
2 small padlocks.
1 golf tee and golf ball.
Styrofoam insulation board.
5 pounds of play sand.
Cut holes in the 4 sides and the top lid of the sump pump basin using a key hole saw and install the speaker grills. Cut a piece of Styrofoam to fit the bottom of the basin and coat it with a light even layer of sand. Set up the golf tee and ball into the center of the bottom of the basin. Hang your radon kits on the underside of the basin lid and secure the lid to the basin using the padlocks. You might need a hook for the radon kits and some holes for the locks.
When you return to retrieve the radon kits, carefully unlock the lid and examine the golf ball. If it has fallen off its tee, you know that the cage had been bumped. If the cage had been moved, the golf ball will leave a history of this movement in the light even layer of sand.
This system is nice because it does not require uninterrupted electricity or batteries.
A quality control check to ensure that the cage itself is not affecting the outcome of the test by hampering airflow can be performed by running several simultaneous tests inside and outside the cage and comparing the results. You should save the results of this experiment should this issue ever arise.
Dress up your cage by adding custom stickers, reminding occupants not to disturb the cage. You can print them yourself or call InterNACHI and we'll do it for you for free.