Buck Regulator Olympics is the current advanced contest in /r/diyelectronics on reddit:

The goal is to build a switching buck DC-DC converter from discrete components that can step down a fairly common input voltage to another common output voltage–in this case, 3.3V

Constraints

• Output voltage of 3.3V.
• Minimum current of 100mA.
• Can not be a prepackaged buck regulator solution
• Must build from scratch using discrete components

Winners

• One winner be picked by a panel of judges including kentaurus712 and RTA5
• One winner will be picked by community votes
• Selection criteria:
  • Cost efficiency (lowest overall BOM cost)
  • Power efficiency
  • Output tolerance
  • Features:
    • Feedback loops
    • error correction
    • overcurrent protection
    • turn-on voltage enables

Prizes

• Both winners will receive $30 gift code for OSH Park

Deadline

• April 30th, 2016