Heres the best idea, I now it aint always the cheapest, but get one of those big display cases. You can get factory seconds sometimes. I've had mine in cases for about 4-5 years now, and they are virtually dust free. What little dust gets in there is easly kept up with. I got 3 of those cases, one had a cracked mirror backing in one section, luckily i got some spare mirror pieces, and placed it in the bad section. Another I got from MAC tools truck. It had ridden in the box and scuffed the plexi glass front. A little time with some auto polish and the scuff is gone. Both I got 1/2 normal price. The 3rd was a gift.
Of course I got lucky, individual cases could work too. Dust, is horrible, and gets all through them, I'll leave my finished kits in the box until I have a case.