Clear coat for hand-painted (acrylic) box

[Anchorman]

Hello! I have hand painted a box with acrylic (artsy stuff, not durable) and now I need to apply a durable clear coat. I have read several threads on the subject. Since it's winter and cold and I live in a 20 m^2 apartment, I don't think I can spray it so I need to paint it with a brush. From what I've understood, polyurethane might be my best shot, no? I've been to several paint and hardware stores, and all polyurethane I've found is meant to be applied on wood (furniture, floor etc.). Can I still use this on my acrylic-painted aluminum box? Also, it's available as both water-based and oil-based, which would be best? Any insights would be very appreciated! 

/Carl

[cloudscapes]

I use acrylic paint too and have found a way to really make it durable. I use clear epoxy resin! most decent art stores should carry some. I wrote a pseudo-guide on this blog:

http://stillepostdiy.blogspot.com/2008/11/using-epoxy-resin-to-coat-pedals.html

I have several other examples of this method on my own blog
http://soniccrayon.blogspot.com/

[Anchorman]

I use acrylic paint too and have found a way to really make it durable. I use clear epoxy resin! most decent art stores should carry some. I wrote a pseudo-guide on this blog:

http://stillepostdiy.blogspot.com/2008/11/using-epoxy-resin-to-coat-pedals.html

I have several other examples of this method on my own blog
http://soniccrayon.blogspot.com/

That looks great, thank you! I will see if they've got something similar at my local art-store