Replying to Ken, who asks:
That's where the spring clips come in- they hold the "sandwich" tightly in the frame. I've attached a couple of snaps to show close ups, and a video (not mine) I found with general assembly instructions.When you get matt board and glass, how can you be sure that the combined thickness will be right ? I got a frame and some matt board but the whole thing slips around.
Hope this helps.
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