Welding

This spell merges two surfaces you touch, such as two pieces of iron, two ends of a rope, or the two sides of a torn waterskin. The contacting surfaces may be no larger than 1 foot in any dimension. 

If this spell is used on a malleable material such as cloth or rubber there is no trace of the weld left after the spell ends. If this spell is used on a ridged material such as stone or metal there is a noticeable trace left after the spell ends. Joins made with this spell are treated as one object class lower with respect to HP and AC. If you wish to combine two objects made of different materials you may attempt a check with a DC decided by the DM, using either an appropriate tool check or an arcana check. on a success, the joins are treated as the weaker material and there is an obvious trace left after the spell ends. on a failure nothing happens and if either material is flammable it catches fire. The join must be no larger than half a foot in any dimension. 

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the maximum size for the join increases by half a foot for each slot level above 2nd