Can I make MagSafe2 to MagSafe1 converter?

"Yes, but, it seems to me, Apple's MagSafe 2 Power Adapters are more discriminating (than Apple's MagSafe ""1"" Power Adapters) of when to switch-on their output. Aftermarket and counterfeit power supplies which are ""always on"" (always supplying ""running"" output potential, rather than a very low potential (to prevent sparking) during no-load state) will work. MagSafe 2 uses same ID data structure as MagSafe 1, so older MacBooks can recognise and accept MagSafe 2 power supplies.

I made a MagSafe 2 to MagSafe 1 converter. It works.

Another idea is to grind a MagSafe bit, to make it match the intersection of MagSafe bit shapes 1 and 2, which I attempted: I ground a MagSafe 2 bit to turn it into a MagSafe Intersection bit.

To test, I tried to use it with a MacBookPro7,1 (13-inch, Mid 2010) and with a MacBookPro6,1 (17-inch, Mid-2010). (If I had access to other MacBooks which have MagSafe 1 inlet, then I would have liked to try it with them.) My 60W A1435 Power Adapter works with both MacBookPro6,1 and MacBookPro7,1. My 85W A1424 does not work, with these two 2010 MBP test subjects."

It is completely possible to do so. Just bridge the pins from the MS2 to MS1. They have the exactly same pinout.