I was at Meijer last night, looking for batting helmets (unfortunately all they had were helmets with like, scallops, and holes in them), and saw these for sale for $10:
And I thought "Hey, maybe that'd work for a dome!" What do you guys think? Granted, I'd have to fill in the hole on the top with some putty, but for $10...

And I thought "Hey, maybe that'd work for a dome!" What do you guys think? Granted, I'd have to fill in the hole on the top with some putty, but for $10...