New answers tagged glue
It's hard to answer this question without knowing more about the model in question. Something like a small Lowell Sphere would probably be made 'unbreakable' by a little squirt of expanding foam insulation inside. A Technic vehicle would be a whole different problem.
Is there a specific scenario in which it should be unbreakable? You definitely should use different techniques to prevent a spaceship from falling apart when dropped from a meter and to prevent a brick wall from separating when hit by a rolling football. For System bricks using larger, longer bricks in overlapping configuration (think real life bricklaying) ...
This is really nearly impossible unless you have a lifetime supply of super glue. A good structure using Technic LEGO bricks will provide better support and a lot more "stick" to each other, making the creation less breakable. Building the structure in which the strongest side will take the most hits/pressure should be an excellent way to make the model ...
Try using double sided tape. But I recommend using the soft stuff so if you hit your head it's not as bad.
This sounds like a job for "Amazing Goop." It's available at Home Depot and other big stores, at least in the US. There are a few varieties, including one for automotive use. It pretty much sticks anything to anything, and once cured, it's on for good. I've used it for gluing LEGO pieces onto a curved metal surface, and was very happy with the results. ...
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