The range limiter, a new constraint type which sets a max distance allowed between attachment1 and attachment2.
This constraint could be useful for a lot of situations, here are some examples of what it could be used for:
Preventing players from leaving a specific area while still being able to walk around without any side effect.
Preventing objects which are affected by physics from leaving the area it is meant to stay in, like if you have an orbit system, and someone is somehow causing the planets to go faster than expected so that it leaves the orbit area, the constraint can prevent the planet from leaving the area and force it back in instantly.
This can also solve the flinging issues with rope constraints:
Without this constraint, you would need to use a lot more items per ropeconstraint.
If this constraint were to get added, it would allow me to prevent physics mechanism and parts from flinging themselves into the void by pure luck.