This test is used when characters attempt to construct large, improvised items from basic materials; when trying to build a rough shelter, a raft, or a rope bridge, for example. The same test can also be used to decide whether emergency repairs can be made to things like wheels and axles.
Construct tests are made against Dex and can be modified by the gamesmaster, bearing in mind how difficult the task is. The GM may decide to split large or complex projects into a number of different construction rolls, requiring the success of one stage before moving on to another. Usually only a single test is made for each stage of construction, no matter how many individuals are involved - therefore even though several characters may have a bonus on their construct roll, only the highest bonus would be used.
The test is made secretly by the GM and the result is noted down. A successful result means that the construction will stand up to whatever it was designed for. Failed tests can have varying effects, according to the amount by which the roll was higher than that required:
Failure by 01-10%: The construction is shaky and good for only 2D6 days of use. After this, it will collapse.
Failure by 11-20%: The construction is shaky and good for only 2D6 game turns. After this, it will collapse if used.
Failure by 21-30%: An unsound construction. Every turn it is used, roll a D6. It will collapse on a score of 6.
Failure by more than 30%: Utterly useless botched job that doesn't even look safe. Falls apart as the last nail is hammered home.
The Construct test is only intented to allow characters to do things within their general talents, encompassing special skills where applicable. It is not a license to build whatever they wish. If players take liberties with this, you should ask them exactly how they intend accomplishing their task and judge the scheme on its merits. After making sure they have all the necessary tools and materials to hand, assign a modifier to their chance of success.