Here's an easy mod you can try if you have the reproduction DMC-H dash, and a dash mat. Securing a dash mat with velcro or some other fastener isn't going to work if you don't want to use glue or adhesive. For years I let my mat sit unsecured on the dash, letting it shift around. When I replaced my original dash, I got an idea to use magnets under the hollow reproduction dash.

Get eight strong magnets. The magnets found in mechanical hard drives are easy to come by and work great: http://onebeer.net/magnet_howto.shtml

Epoxy four of the magnets to the underside of the dash
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Once your dash is installed, protect the dash and windshield, and put matching magnets on top of the dash.
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Spread some epoxy on the tops of the magnets (be careful to not get any on the dash, windshield, or interior in general) and carefully lay down the mat. Once the epoxy cures, you can remove your dash mat with its perfectly positioned magnets.
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Get some felt and have it sewn, or glued to the underside of the mat, over the magnets. The felt will protect your dash from scratches.
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Your dash mat should snap right into place when needed, and it’s easy to remove without a trace.
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Bonus: When installing the dash, adding a washer and threading on a nut under the center of the dash can be tricky with little room for wrenches and fingers. Use a magnet on top of the dash right over the studs. The washers will jump into place, and stay put while you thread on the nuts.
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