How to express longevity?

You can use a scroll specially mounted with calligraphy, or you can use a square madman.

If it is smaller, you can match it with a dark brown border and cut out lace to make it look like a regular prism and get a red Chinese knot.

It is more appropriate to mount it in a gold frame. You can use glass or transparent acrylic board as the panel, which looks more upscale and makes the old people very happy.