What is the best glue for Legos?

According to Lego artist Eric Harshbarger, the best glue for Legos is plastic cement. This adhesive, used by plumbers and sold in hardware stores, acts as a solvent that bonds the styrene ABS plastic of Lego bricks. Harshbarger recommends Oatey brand all-purpose plastic cement for permanent Lego assembly.

Harshbarger and other Lego artists, such as Sean Kenney and Nathan Sawaya, use adhesives in their large works to prevent damage during transit and gallery display.

The Lego company itself uses solvents such as MEK and GBS to bond the sculptures at its Legoland parks, as well as in certain products, such as its Star Wars minifig magnets.