Ok, so, as most of you have probably figured out, mexes have an uncanny ability to deprive you of a lot of mass when you rebuild them.
This is due to the fact that, when you build, say, a T1 mex ontop of a T3 mex wreck, the T1 mex gets the "50% build bonus", like you get when you build a building over a wreck of the same building.
This is a problem because you never get the mass reclaim from the T3 wreck, and all you get is half a T1 mex in return. Not cool, wastes a LOT of mass.
There are now two ways to avoid this:
Remove the rebuild bonus for mexes not of the same tech. This means that, if you rebuild a T1 mex ontop of a T2 or T3 mex wreck, you do not get the rebuild bonus, instead, the builder will reclaim the T2/T3 mex wreck, and then start building a T1.
However, if you build a T3 mex ontop of a T3 mex wreck, you will still get the 50% build bonus. This is the first variant of the fix.
The problem here is that most people generally want to reclaim the mex wreck first, in order to get most of the mass back (a T3 mex is worth quite a lot of mass).
For this purpose, I'm also uploading a variant of the fix that disables the rebuild bonus entirely (if you rebuild a T3 mex ontop of a T3 mex wreck, the builder will reclaim the T3 mex wreck first and then start building a T3 mex from scratch)
Both of the fixes are in the attatchments, now it's up to the people to see which they find to be more intuitive/useful/etc.