How can I keep machinery components from breaking under stress?

I'm attempting to construct a very-large sliding-block device in Little Big Planet 2, but every material I've tried to use—glass for less friction, sponge or pink/orange foam for minimal weight, metal for structural integrity, cardboard and wood just to exhaust the options—the result is the same: a powered block can push another block, but as soon as I attempt to push two unpowered blocks, the middle one breaks and pops out of existence.

Am I overlooking a material or a setting somewhere to keep my structures from destroying themselves, or is there a better way of going about their design to avoid this particular characteristic of LBP's reality?

Try using a material tweaker from the tools section. Stick this to your machinery and set indestructible to yes. That should do the trick!

Additionally, the material tweaker will allow you to set the friction of the object from 0-100%.