Doing Time By Sand is a method whereby prisoners can greatly reduce their sentence time, by engaging in the work of converting smooth sand to rough sand, one grain at a time.
The entire punishment may be summed up in the process of adding crenulations to individual grains of sand in order to convert
them to being usable in the building process.
This is because the sort of sand that is found in vast quantities in places like the Sahara desert is totally useless when added to cement, as the individual grains have been polished too smooth to effectively allow them to bind together in the aggregate.
This means that many countries are causing huge environmental problems by simply stealing massive amounts of sea-based sand, the grains of which are already suitably pitted and crenulated. (see subsequent links)
The solution is of course to convert large volumes of existing smooth grained sand to that of the "rougher", useful variety, but who's going to do that? This is where the prisons come in play a role in the idea.
The actual process involves a group of prisoners operating a piece of equipment and periodically swopping roles. The equipment consists of conveyor belt of hollow vertical needles, each of which terminates in a microscopic gripping claw. Each needle is "dipped" into a reservoir of smooth grained desert sand, and the suction attracts an individual grain. Once in place the needle's end jaws close over, to lock the grain in place.
The prisoners are arranged in a row along the length of the conveyer belt. Each grain is checked by the first prisoner as it passes by via a powerful magnifying glass, to ensure that it is firmly held in place by the needle's gripper. The next set of prisoners all have similar lenses, but also sets of semi-automated micro drills that enable them to make the vital holes and crenulations in the passing grains. The final prisoner acts as quality control. The completed grains are deposited in bags ready for certification as suitable for use in the building trade.