i found this gilded wood frame (sorry no before photo) at the thrift store in September--it is quite large (over 4 feet wide x 2 1/2 feet)
it contained a large fake painted scene, which i removed and then i spray painted it in a black semi gloss.
initially i was going to insert cork or do a chalkboard, but when i removed the picture the oversize staples remained and i decided to run some 19 gauge wire from side to side (looped around a staple on one side, strung across and looped onto the staple on the opposite side).
the wires are not permanent and i can utilize the staples should i decide to insert a piece of linen covered cork, a chalkboard, or a piece of metal if i want to change the look of the frame.
Tip: I use 19 gauge wire quite often in my DIY projects. you will find it in the rebar section of the hardware store for a fraction of the cost that you would pay in the other aisle sections of the same hardware store. it usually comes packaged in rolls wrapped in paper (also note it can have a bit of residue on it + you might need to wipe your wire pieces down):