DIY Plastic/acrylic safe scraper

[gonzobluefuzz]

Been looking around for algae scrapers that will not scratch an acrylic tank and came across a post here about credit cards being good scrapers. They worked great but after breaking /cracking 3 or 4 cards due to my ham fisted algae assaults the little gerbil started running in his wheel and this is what I came up with.
Was bored the other day and thought I'd see how this turned out. Seems to work great....but next gen will have a bigger handle than what I put on this one.
The end result is mostly plastic with all metallic hardware below the surface ....so even a Murphy prone individual (such as myself) would have a hard time scratching the "glass" !!

What you need

Chunk of dense rigid plastic
10-32 tap ( I'm sure smaller or bigger wouldn't hurt) and corresponding drill bit
Drills 1/16", 3/16"
Countersink (or a big!!! drill bit ½ inch or so)
File
2 screws (10-32counter sunk or equiv. for your setup) 
Hacksaw/jig saw/band saw which ever
Clamp or vice
Strait edge/square
Expired credit card/ gift card (free for the asking in many locations)
20 minutes - 1 hr of your time depending on how you are equipped

Take your piece of plastic and cut 2 pieces to a size that you feel would be convenient (keep in mind the more you leave now the more you gotta hack away later)
Clamp both pieces together and get your file working along the long edge so as to get the two pieces as close to flat and flush as possible (use your strait edge as a guide or alternatively if you have access to a belt sander give each piece a touch until flat)

Drill a 1/16 pilot hole thru both pieces.

***note remember to keep track of which side is which

Separate your pieces ......on piece #1 drill thru pilot hole with a 3/16 drill bit and countersink the hole so the head does not protrude from the plastic. On Piece #2  drill w/ #29 drill bit (or which ever you tap size needs ) and run your tap thru it (make sure you go slow to prevent as much cracking as possible)
Using one of your screws join the 2 sections and drill another pilot hole at another location. Repeat the previous 2 steps @ another location. Same or opposite faces shouldn't really matter (I chose opposite)

Grab one of the pieces and lets begin the fun part   using your trusty file slowly cut away a step just slightly narrower than the thickness of a card on the side opposite side of the countersink. Test fit on a regular basis you can always remove more. 



Once you've got the step to your liking file edges of the unit to the shape and contour of your preference.

Now put the thing together add the card and voila.  I chose to cut the card in half to get rid of some of the flex

My down and dirty result looked like this



I know that there are many commercially available "safe" scrapers around, but the mood hit me  Besides It's a cheap and easy project that burned a half hour or so

Let me know what ya think.

BTW:seems to me as tho I'm not much of a technical writer......so any q's or omissions ....fire away

Cheerz