You apply it with a fine brush. It welds the parts together. You don't drown it with the lacquer thinner, and partly use capillary action to get the thinner into the joint. It doesn't ruin the plastic, unless you drown the parts, which is not necessary . It leaves no residue. It cures relatively fast.
You can also use "MEK" which is also a solvent for Styrene. I purchase both in "Quart" cans, at the local Home Depot, or Canadian Tire. Sometimes you need to look for them in the "Auto Body shop supplies section., or the paint department.
Most of the hobby shops sell the same stuff, as liquid plastic cement, in small bottles with a brush, srew on lid...at anywhere up to $4 a bottle (2 oz)… A quart is usually less than $4, in some cases, and lasts a loooooong time. Acetone also can be used.
Another use is for repairing Bachmann plastic parts, even freight and passenger trucks (Bogies)
The least useful is the old tube of Plastic aeroplane glue...avoid it if possible.
DON'T BREATH THE FUMES, OR LIGHT YOUR JOINT NEAR THE STUFF....!!!