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#1 It's a 16x16 platform, with edge_white2 or mbu_edge_white2 scaled at 1 1. Just click to make a wall, then decrease it to those dimensions. Once you have a trim section, you can duplicate it over and over for the whole level.

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#3 Why use Quark, Constructor was built TGE, TGEA which Marble Blast was made from. Constructor is much more efficient to use.

#4 Consturctor does not export its DIFs to MB. Rather, it's TGE/TGEA. MB is an ancient engine of which its DIFs are solely based on Marble Blast Map2Dif.exe . Constructor and QuArK are both MAP makers, but its the EXE that you need, thus you need someone with Win-OS in order to convert the MAP to DIF. Constructor also has limitations that QuArK doesn't have as well as other bugs [like maps not converting or messing up and others] whereas QuArK has different bugs.

#5 When it comes to making difs for MarbleBlast, all of Constructor's bugs are unseen until you finish and try to convert, while all of Quark's bugs are apparent right as they happen because Quark's limitations match marbleblast map2dif's limitations more closely than Constructor's. And personally, I find Quark easier, as does a majority of these forum members.