This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.
The HM-2 is the godfather of all other heavy metal distortion stompboxes. While it was first introduced in the '80s, it's still a highly regarded circuit for metal applications with its high gain and crushing lows, especially if you live in Sweden. Said crushing lows are thanks to the gyrator tone stack (not something you see all that often). Original units only have high and low tone controls, but it's easy to add a mids control, and the layout below reflects that. If you don't want the Mids control, simply connect the Mids 2 pad to lug 2 of the Highs pot. It's a fairly big layout, but you should be able to fit it in a 125B without issue, and if you're really precise with your drilling you might able to squeeze it into a 1590B.
Update July 13, 2016:
Updated the layout so that the ICs are getting full 9v. Tone stack pots may need to be reduced to 10k.