Way back in time when the earth was flat I had the opportunity to do costume work in a small teaching theatre. For quick kilts we found some cheap bolts of plaid (not tartan) heavy flannel. ripped them to appropriate length, then folded to "sett" some pleats, pressed and machine stitched the whole mess in position at the waist and a quarter of the way down. Velcro closure to make them very adjustable. Various old brooches were used as kilt pins (for the weight). Wide belts with tacked on tin wrap over the buckles. cinched about two inches down from the top of the "kilt". some jack chain through two punch holes in the belt hold "sporrans" (Cheap fanny packs withe the regular strap cut off and a piece of black canvas stitched or glued to the front in sporran shape. hung a couple of tassels on with hot melt glue. Did fine for the show, the lighting kept the details hard to observe. Several of the student "actor-extras" liked the kilts so much they wore them on campus.