The third hand clamp was developed to hold tubing together for butt welds. Designed to snap onto the ends of tubing and hold them so you can safely tack it together without struggling to keep it in one place.
The are available in the most common sizes and also as complete kits.
They clamp around 50% of the tube so there is plenty of room to safely tack without heating up the material near the clamp, some common sense is required for use.
Please remember these are made of a composite material and are only meant to hold in place while tacking, not welding as they will melt.
Industries as varied as automotive and toy-making use acrylonitrile butadiene styrene (ABS) for its durability and formability.