(re-post)
Maybe they are making elastic better than they did when I was younger; it has been years since I've heard anyone say, "Your slip is showing".
Recently I began looking for a nice piece of material to make another slip and in the perusal at my fibre archeological'digs'(church/garage/rummage sales) I came across – and considered – red flannel, fine Italian wool, vintage muslin bed sheets, crocheted cotton table cloths and runners, linen napkins, lace handkerchiefs …
Since I wear my skirts long I tend to have kick-pleaats in them and at times my slip does 'show.'
Silk scarves came to mind. The first to appear was at the Francophone church rummage sale – the one in lower right, made in France, enough for two panels. One of my maternal grandmothers was French so this seemed appropriate. (I had three maternal grandmas; childbirth claimed two of them way back then.)
The hand painted scarf in the middle presented next at the mid-week church sale and has glorious colourful fish tumbling down it. It is signed but no luck googling.
Then, at St. John's bazaar on the weekend the golden pillow cover surfaced. It's a Klimt. Removing the zipper and the four (four!) lines of stitching along two sides resulted in a suitable length of fabric.
At the moment the decision is to use only the two vibrant pieces but won't know until I actually begin to work on the slip.