(1) From the meaning of the question, it can be seen that the rectangular body is y mm long, x mm wide and 65 mm high.

The volume of the rectangular frame is 65xy cubic millimeter.

So the answer is 65xy；;

(2)∵ Rectangular body length y mm, width x mm, height 65 mm,

∴ The surface area of a cuboid =2(xy+65y+65x) mm2,

In addition, the area of the corner paste inside accounts for 15 of the area of the cardboard on the surface of the cuboid.

∴ The cardboard area required to make such a cuboid * * = (1+15) × 2 (xy+65y+65x) =125 (xy+65y+65x) =125xy.

∫x = 40，y=70，

To make such a cuboid * * * requires cardboard125× 40× 70+156× 70+156× 40 = 23,880 square millimeters.