Ryanair fly to Hahn, about the same distance as Frankfurt but flights are a lot cheaper, although it is in the middle of nowhere and you have to fly Ryanair, which is an adventure in itself.
best one is Lux but some say paintball is banned in Lux, some say it's not. http://www.tpll.lu/ is a tactical paintball league in Lux but nobody replies to mails, so it may be fake
if someone finds out if it's really banned in Lux please let us know
All I know is we were flying out of Luxemburg a couple of years back a group of American players were told that they would have had their markers taken if they had been noticed on the inbound flight, but as they were leaving they would be allowed to keep them but would not be allowed back in the country.