My idea is to limit different features(such as physics gun,tool gun,weld gun,etc.)to certain teams.
This way you could have games on you server so that one team would have building tools like weld gun,physics gun,rope gun,etc. but that team would'nt have any guns and the other team would have all guns but no building tools.
Then the team with building tools would rely on their building to survive while the other team tries to kill them with their weapons.
You could also use this so that if someone is messing with other peoples contraptions then you could put them on a team that can't use any building tools.