Eh, brass knuckles aren't too hard to find. My grandfather has a set that belonged to his father, and I have a beltbuckle that features a decorative set. If nothing else, get a semi-rigid material, and carve your own. With a drill, a dremel, a jig saw and some sand paper, you could whip out a mean replica in no time out of a small piece of scrap wood. Yeah, I use the rockabilly influence, combined with a little punk, and some good-ol' rocker style, so a lot of my ideas/opinions/questions have that slant. As for airbrushes, not all use the siphon (blow over a hole) style. Mine is actually gravity feed, with the liquid cup resting on top of the barrel. Alright, I've been working on a few designs, but some of them definitely aren't things that I'd wear, but would fit into others style well: Dark blue, fresh denim. Preferably a very fitted bootcut. Cut the slits in the hem, and attach 3 antique-finish brass buttons. Pair with a sweater, some chunky leather shoes, and a pea coat. Distressed denim, possibly with a knife crease. Along the bottom hem, airbrush a thinned black mixture into a variety of gothic (the period, not the "pity me" style) crosses overtop of each other, so that they overlap to the point on not being able to distinguish them at the bottom, but become more separated and visible towards the top (about 4" up). Almost forms a "skyline" effect, with a Victorian graveyard motif. Alternately, trace this overlapped pattern onto black fabric, cut that out, and sew it onto the denim, using a tight embroidery-type stitch to define the edge. Would look good with "biker" style boots, possibly in a distressed black leather: see the Kenneth Cole Peacemakers or some of the Dsquared styles. For a more "urban" edge, distressed graffiti (complete with simulated drips for authenticity) would work nice, possibly on Sean John or Phat Farm style pants. Either a simple black tag could be used, or even a full-color "wildstyle" image. If you have access to silk-screening equipment, use a classic image such as "The Creation of Adam" either in the original colors, or a highly stylized high-contrast single color abstracted version. If you're artistically inclined, this same effect could be achieved with a stencil and either an airbrush, or hand stippling. On a pair of tighter fitting denim, preferably with a blue/white stripe (similar to train conductors hats) or an overdone 80's acid wash, stencil or otherwise transfer the cover art from the Clash's London Calling, possibly on the thigh, slightly above the knee, or on the back of the thigh, overlapping onto the pocket. As some designers have done, cut apart two different kinds of denim (or other material) and sew the front of one pair to the back of another, and vice versa. Also, transfer the back pockets to the other pair for added interest. Although these would probably be easiest to do with an airbrush, a lightbox and some other art materials, they could just as easily be done with any sort of color-fast pigment and widely available craft tools (stencilling brushes, etc, etc). One thing I've always wanted to do (and this goes way beyond just customizing a pair of store-bought pants) was to make my own pair, but instead of placing the seam down the side, make a single seam on each leg, spiraling down the length of the pants, sewn with either a contrasting color thread or even a thick yarn/cord. Just some ideas. I realize that most of these are probably a little more extreme than most people would care to go, but you can take little ideas here and there and apply them in combinations to make a pair of pants that are truly unique to you. Also, look at the work of your favorite artists for inspiration. A particularly good one would be Andy Worhol. Some of his simpler designs would be a great inspiration for some custom ideas. Look beyond the fashion world. For example, the way a cigar is rolled may be an interesting source of designs, as would a tile mosaic in the lobby of a hotel. The point of modifying clothes is to make them your own, so take a hard look at the things in life that you truly enjoy.