There's a couple plans available here.
The most straightforward and potentially problematic one is around Tears of Rage and Akroma's Will. Set it up with some tokens ahead of time - or just use a Fury Stormed Benevolent Offering the turn before - and you can easily swing for hundreds of unblockable damage. The fact that this is all basically tutorable from the CZ might make it a bit repetitive tbh, so I might end up cutting tears of rage.
The second plan is to defend a innocuous-ish planeswalker with anti-combat sunforger tech, then use Repeated Reverberation to triple a planeswalker ult and have a jolly old time. In some cases - Gideon, Ally of Zendikar - you can pretty much just go. +3/+3 permanently, baby. But damn do I want to get a triple chandra ult or a triple ajani ult at some point. That just seems fun.
There's also some fun madness synergy for the commander. Nothing gamewinning, but some nice pieces to make him more effective once he's fetched the forger.
And if your other wincons fail, you can always just beat down with some decent RW beaters.
OP:
I've been a big fan of Sunforger ever since it was printed, but it's been hard to find a good commander to exploit it. Akiri, Fearless Voyager was a great option, but it wasn't particularly motivated to go all-in on sunforger. In general, the problem with going all-in with a RW deck is that you only have a handful of ways to get sunforger into play, so you can't count on having it.
Enter Plargg, Dean of Chaos.
Obviously using Plarrg to guarantee hitting sunforger requires a pretty stringent deck restriction - no nonlegendary spells below 4 cmc. Or very few, if he's to be at all reliable. But on the plus side, Plargg himself is our 2-drop, so the necessity for ramp is somewhat diminished. And we can also play all the cheap legends we want, including hits like Umezawa's Jitte, Sword of the Animist, Blackblade Reforged, Mox Opal, Shadowspear, Mox Amber, Sram, Senior Edificer, Feather, the Redeemed, Zirda, the Dawnwaker (and companion is definitely on the table here), etc. The other good thing is that plargg has a looting ability that will still give him utility after he fulfills his primary purpose of putting sunforger into play. This could even let us play cards like Violent Eruption or Incorrigible Youths on-curve. Or we could just play augusta, dean of order instead if he dies after getting sunforger into play.
As far as abusing sunforger, unfortunately we're pretty restricted on spells since we can't run any of the usual 1, 2, or 3-cost instants. This eliminates Tithe as a way to get Mistveil Plains, so we'll be relying on fetches to hit it most likely. Given that we're massively warping the deck to maximize sunforging, I think we'll want to be able to equip it as frequently as possible, especially as an instant to protect it from any disruption (Cosmic Intervention is a nice add on this score). To that end, Auriok Windwalker and Balan, Wandering Knight are easy inclusions. Brass Squire I think is worth it even as a spell that's hittable with Plargg, since it means that, unaided, we'll always have both sunforger and a way to equip it strictly through the CZ. I can't think of any other 3cmc or less spells that would be worth including, but I'm open to ideas. Could throw in a random versatile answer like Generous Gift, as a backup plan to recycle with Plargg and mistveil if sunforger gets exiled somehow.
I just realized that plargg + mistveil means that sunforger can't be effectively removed unless it's exiled, which is *chefs kiss*
Ofc, an alternate build would be to use Plargg AS sunforger, and pack the deck with a versatile suite of answers which are likely to solve most problems. Idk how feasible this is with the random element, though. There's a lot of strong niche answers that wouldn't really fit, so I worry that it'd basically just turn Plargg into a 5-mana vindicate dispenser which isn't nearly as fun as sunforging up Wild Ricochet and Comeuppance to blow people up.
EDIT: evil dirk would like to add that an alternative strategy based around Restore Balance would also be a viable way to build Plargg...
EDIT 2: even eviler Dirk would like to add that Sundial of the Infinite and Last Chance (or similar) with Mistveil Plains is also probably a strong deck...