This falls under the same area of law as drawing the symbol on your friends bag cause its cool. As long as you keep the batches down and don't sell them for personal gain you can't get slapped with a legitimate case. I say legitimate case because anyone can try to press charges for anything, they just get thrown out. Until Blizzard starts making their own caps, low batch quantities means no trademark dilution and limit the distribution showing that it is not for personal gain. Also it is made abundantly clear in the forums that you are giving Blizzard the credit for the Logo and just want to rep. their product because you like it.