Over the years I have come across many a holder for securing a handheld stop sign inside a school bus, some commercially available while others were usually made by the shop or bus distributor. One of the best I've ever seen is two sheets of ¼" thick black ABS plastic cut to the outline of the stop sign but larger and sandwiched together around the edges using industrial strength adhesive and rivets. The space between the sheets allows the sign to easilt slide in or out and offers superior protection over straps or clips. If anyone knows who manufactures this holder or similar or can point me in the right direction I would be thankful.
58Toyopet (1988 91pax Tandem Crown 671Turbo Allison HT-740)
I've never seen a sign holder like your describing, but Besi makes seat covers with pockets on them that are perfect for stop signs. I sell Besi covers and could help you out to find one that will fit and match your color. Just click on the link in my signature and give me a call if your interested