Design Criteria For External Crossover Box

Does anyone have any thoughts on an 'ideal' design scenario for an external crossover enclosure, one that provides the best sonics?

I'm working on upgrading a pair of Maggie 3.6R's and want to replace the existing crossover boxes with larger boxes that will allow more flexibility for upgrading components, and will also accommodate the internally mounted tweeter x-over which I plan to move.
My thoughts are to use a non-metallic enclosure, maybe from plastic or acrylic, perhaps even wood. However, I'm thinking of utilizimg a large copper EMI/RFI plate, that sits above or below the enclosure and about 2" away from the components. I could then experiment with/without the copper plate, and also bonded/non-bonded to ground.

Or....would it be better to use a grounded metalic enclosure in your opinions? I've seen a company on eBay (via another thread on AG) that can make a copper amplifier chasis...would that approach be better?

Many Thanks for any input.

Very few have a lot of experience with various materials to make there crossover box out of. I made mine out of maple because its easy to work with, is rumored to "sound good", looks good and offered piece of mind over using a metal or acrylic box that could introduce static electricity into the mix. I made mine point to point and a metal box would have me worrying about something shorting out. Another benefit to using wood is the fact it can be changed very easily. More important then what the box is made of is of course finding component that suit your taste and setting them up as to optimize there performance. Make sure you keep your inductors on different planes, this will help create a blacker back ground and reduce any interaction between the coils. Build your boxes larger then you'll think they need to be so you can move things if you desire, its best to have the room and not need it then the other way around. There are a lot of tweeks once you get your crossover built, it depends just how far you want to push the limits. You can expect even with a moderate crossover and internal rewire a 60% increase in over all performance. Increased bass response, much greater transparency and detail, more articulation top to bottom, greater dynamics at lower and higher volumes, wider/deeper soundstage, creepy good imaging(a quick funny story about this, I was talking to a friend how you can distinctly hear things from behind you with some discs, keep in mind my system is strictly 2 channel. He laughed and said RIIIIIIGHT, he came over and listened and could NOT believe what he was hearing from above and along side him! They didn't do that before the upgrades) in short they are hardly the same speaker. These are just my experiences, I have no knowledge of anyone using a metalic enclosure with modified magnepans- I am curious what the differences would be!

btw the internal crossover houses the majority of the mid and tweeter crossover not just the tweeter. Also be aware the new components will be MUCH larger, so plan on this when you design your boxes. I have caps that are nearly the size of soda cans in my crossovers!

This is a fun and ultimately very fulfilling project have fun with it.
Thanks Tim, I did the fuse bypass mod on the weekend and also shorted out the tweeter attenuators, the results were excellent, the sound is more dynamic, but at the same time more fluid and effortless.
I just ordered Cardas binding posts to replace the cheapo maggie posts, that was kind of expensive!
I found a site that sells air core inductors, just wondered if you had an opinion on those, and what you've tried. Also, I'm looking round for caps, I've seen the Solens, and also the Cardas caps (not certain if the Cardas have the right values), wondered what your thoughts were? I don't want to spend a packet on caps, maybe $200 max - is that worthwhile or should I get the cash together for more expensive ones?
I'm going to use Cardas hook-up wire for the internal rewire, not sure if there is anything better out there.
This is exciting stuff - things are starting to sound great!!
I will send you a detailed email early next week, I am super busy right now and will be away for the weekend. I still have your email address we can go more in depth about the next step and some options you have, don't do anything in the mean time, just save lots and lots of money :)
Thanks Tim, I couldn't help myself, I received the Cardas binding posts from yesterday and just had to install them. The main motive was that it let me remove the shorting wires and use biwire cables with spades. It was a pain in the rear trying to solder inside the crappy x-over box, but after 3 hours and numerous burns - Holy Christmas! Using Sonoran Signatures on the lows and Audio Insurgents on the highs, the bass on these speakers just went into another league!

Looking forward to learning from your experience and working out what to do next.
I read a lot of stuff at the asylum, and one concern is what prompted this thread - the enclosure. I heard people say they had really bad results with metal, wood, plastic - which doesn't really leave many options!!
Others seem to have come up with ways to suspend the components away from the enclosure, someone even talked about having caps suspended on pieces of cotton thread! though I don't know if this was ever tried, others used packaging peanuts!
Oh mamma...