Once a weapons HP are completely depleted the weapon is destroyed. A weapon that is damaged but not destroyed may have its effectiveness reduced if the GM decides. The character can rolls against this skill when attempting to create new devices. Depending on the device the GM may have the character roll on another skill in addition to this. The character must still pay the CP cost for any devices that they wish to build, but they don't lose any points if they fail their rolls.
Players can only attempt to invent a particular device once per session.
An optional ability the GM can allow to use with this is an Invention Pool. The player must assign CP to a permanent pool for this, they cannot simply use unspent points. This ability allows the character to create one-shot inventions with a successful Inventing roll. After that session is over the invention is gone and the points spent on the invention return to the characters Invention Pool. This is to compensate for the lack of one shot inventions in the Rules Upgrade.