In this photo are four MagSafe plugs, displaying stock and altered MagSafe bits. From right to left: MagSafe 1, MagSafe Intersection (altered MagSafe 1), MagSafe Intersection (altered MagSafe 2), MagSafe 2.
I used an electric motorised metal grinder tool on MagSafe plugs. I wanted to reshape them from wide (MagSafe 2) and tall (MagSafe 1), to the MagSafe Intersection. A "MagSafe Intersection" plug fits in both generation MagSafe socket–inlets. However, a fitting connection made from a converted/modified/hacked MagSafe connector is not necessarily functional. All MagSafe 1 power sources should work with all MacBooks which have MagSafe socket–inlets. However, MagSafe 2 power sources are not necessarily backwardly compatible with MacBooks having MagSafe 1.
While in standby state, an Apple MagSafe power source emits very low potential (to sense the sink). I tested my MagSafe 2 to MagSafe 1 converter with a MacBookPro6,1 and a MacBookPro7,1 (17-inch and 13-inch, Mid 2010), and with 60W and 85W Power Adapters. The 60W Power Adapter worked (MacBook identified, accepted, for run and charge), while the 85W Power Adapter rejected this sink. Because my handiwork is sloppy, I suspected that my converter was rejected for electrical traits (likely, conductance between poles, or resistance).
I decided to modify a 85W plug, remove material from its bit to make it be a MagSafe Intersection bit. This altered plug does fit in the MagSafe 1 socket. I tested it with a MacBookPro7,1, making a fitting direct connection, and the 85W Power Adapter rejected this sink. So, this 85W MagSafe 2 Power Adapter seems to be more selective (pickier) of its power sink/load, than 60W MagSafe 2 Power Adapter, and than MagSafe "1" power adapters.
Conclusion: a "MagSafe 2 to MagSafe 1 converter" is less useful than a "MagSafe 1 to MagSafe 2 converter". I discourage you to spend your time, money, or effort, on trying to convert MagSafe 2 to MagSafe 1. I opine: MagSafe 1 outlets/plugs/supplies are more useful than MagSafe 2 parts, no matter whether you are a hacker or a "everyman" consumer. Apple's own 'MagSafe to MagSafe 2 Converter' (order MD504, model A1464) works well.
My MagSafe 2 Power Adapters which I tested:
85W Model A1424 (LITEON TECHNOLOGY CORPORATION) © 2012. Standby sense potential is around 3,15 V.
60W Model A1435 (DELTA ELECTRONICS INC.) © 2014. Standby sense potential is around 0,6 V with occasional spikes around 9,5 V.