NI$HANT:
I didn't write using hobby motors i assumed that fact , as per the tutorial he is following most probably the motors would be Hobby grade(its very rare but not impossible to destroy multimeter's with these type of motor's) not to expect a RC Heli Motor,well you have been specific im fine with that.
Well - I suppose you could assume that; but others may read the process, and think they could apply it to a larger motor; and indeed, even my steps will only allow you to test only up to a certain size motor. In fact, I'm not even sure how you would test an unknown but very high-power DC motor (say perhaps a DC gear motor for a motorized wheelchair for which you don't have specs). You most likely couldn't pony-brake such a motor - not safely, anyhow. I wonder if anybody has suggestions?
NI$HANT:
I had a remedy to it too!, inserting a Aluminium plate that i custom cut from some scrap at my workshop and made sure it fitted in tight so the transference of heat to the plate happens and then giving the shape of a wing to the excess of plate getting out of the bottom IC's can be worked out.
Interesting - I know that there exist clip-on heatsinks for the L293 in its "standard" configuration. I still wish I had an explanation why or how it can work "stacked", since it has those BJT outputs (I've read numerous warnings not to try and parallel multiple BJTs, as they'll fail - and this would seem to be an instance of this)...