I don't really like this card. I know that a lot of people have tried to use Rack/Vise together to ensure that you're going to take some damage unless you can keep your handsize within that narrow 3-4 range...
But it's painfully obvious that this is what this card was designed for...
Only problem is, that such is not the correct use for Rack or Vise...
Still, I suppose it's possible to build a deck around it...
Some similar artifacts...
Pauper's Cage
The Rack (broken)
Black Vise (even more broken)
Wheel of Torture
Iron Maiden
Viseling
Rackling
Cursed Rack
Miser's Cage
Scalding Tongs
Thumbscrews
Copy Artifact (costs only two mana and can become any of these, including Skullcage)
Most of which (but definitely not Cursed Rack) is outright better than Skullcage and could also be used in conjunction with it...
The advantage I see with Skullcage is that you are not concerned about emptying anyone's hand or filling it for that matter...
You only have to make sure that it is either below 3 or above 4, then the damage kicks in and is the same every time...
The color I see being used here to get that effect and keep you alive while Skullcage does its work is (sorry, Train) blue.
The reason? Discard is not instant speed generally, and some opponents are resilient and able to keep a full hand...
Bounce spells, on the other hand, let Skullcage do its work...
If they have below three cards, don't bounce stuff until after Skullcage hurts them. If they have three or more cards, bounce stuff. Easy...
Now I'm not positive as to how you would want to go about this...
Boomerang (the best)
Capsize (insane)
Rescind
Temporal Adept (really cool)
Sunder
Evacuation
Hurkyl's Recall (can't use Rebuild--it would bounce your Cages)
Seal of Removal
Word of Undoing
Rushing River
Erratic Portal
Equilibrium
Unsummon
Man-o'-war
Snap
Stern Proctor
AEther Burst
AEther Spellbomb
Waterfront Bouncer
Noetic Scales
Barrin, Master Wizard
Chain of Vapor
Echo Tracer
Time Elemental
Hoodwink
Cowardice
Regress
Wash Out
Curfew
Sigil of Sleep
Distorting Wake
Withdraw
Crystal Shard
Recantation
Glowing Anemone
Echoing Truth
Into Thin Air
Churning Eddy
Repulse
That's plenty. Now you're going to have to decide what to use. I'd go with some countermagic, a considerable supply of bouncing stuff, Skullcages and maybe some of the other artifacts that are similar to it (listed above somewhere). Umbilicus also might be nice. You'd also want stuff to generally slow the opponent down. Mana Short, Strip Mine, Rishadan Port, that sort of thing. Lastly, some artifact mana and Tinkers to bring in the Cages and speed yourself up...
The other way I think it could work would be U/B. That would allow more for reducing the opponent's handsize and could deal with different types of threats more easily perhaps. As well as bringing in tutors...