I am TheApexhat, and I'm here to ask you a question.
Is a man not entitled to a cube environment he enjoys? No, says the man in WUBRG, it must include a variety of colours. No, says the man in Cardmarket, you need to buy lots of cards for it. No, says the man in WotC, it must include Universes Beyond cards.

I rejected those answers. I chose something different. I chose the impossible. I chose...

a mono-red cube

A place where the goblins would not fear the Wrath of God, where the artificer would not be bound by petty graveyard hate. Where the Dragons would not be burdened by countermagic!
And, with the help of your card suggestions, the mono red cube could be a good cube environment, as well.

All in all, I've tried to make a cube in which one can explore the depth of the most shallow colour in Magic, Red. Featured are...

Big artifacts - cheat out back-breaking artifacts with Daretti, Copper Gnomes, Trash for Treasure and Goblin Welder.
Small artifacts - recur eggs and Myr Welders the world over, and go for a combo finish with Krark-Clan Ironworks
Goblins - it wouldn't be red without them.
Elementals - its better than you think!
Storm - the cube has a single copy of grapeshot, but a myriad of creatures that grow bigger or ping based on spell casts.
Madness - despite the lack of black, there are many potent and powerful spells to accrue additional advantage from your rummaging.
Big Red - not much cheating here - just draft all the ramp and big boys, then smash face with dragons.
Burn - Spell + creature + turn sideways + win

Notes:
Make sure up to ~70 interactive spells that are easily castable
Add more card advantage spells (?)
Consider lowering curve more; currently dedicated aggro is still slightly too slow - maybe increasing burn cards allows for it to be good(?) - lean more into tribes to buff aggro.
Add actual lands and ways to get lands out of decks.
Add more artifact removal