Magic Coin Bank

[DickB]

This is my take on the Magic Coin Bank that I am making for my granddaughter's birthday. It will be fun to see her reaction. If you've never seen one before, it is a (roughly) cube-shaped box with a window in front. A front-surface mirror divides the box diagonally, such that when you look into the bank it appears to be a whole, empty cube. Front-surface mirrors have no distortion due to glass in front, often used with lasers. In this application it makes the seam between mirror and sides and bottom virtually disappear. I found a pair 4" x 6" mirrors on eBay for $15 with shipping, but there are various specialty suppliers. Choosing mirror-image graphics inside the box enhances the illusion. Coins dropped into the bank stay to the back and on top, giving the illusion that they disappear.

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All the parts were made on the Carvewright from 7/16" hardwood stock, which is readily available at my local home centers. I used a carved pattern for the miters, and they came out really well. Very handy if you don't have a table saw or other means to make mitered corners.

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I'm using a carved Celtic pattern on the outside and a matching, colorful version on the inside. Right now I'm just prototyping the insides with plain paper, but will use adhesive-backed paper to finish. Also, I'm using the back side of my front-surface mirror in the photos to protect the front surface, which currently has a protective film on it. I don't want to risk scratching the mirror before final assembly.

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I've got a simple twist-lock mechanism to access the bank - didn't want my granddaughter to loose a key.

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I'm still designing the front face frame, which will hold a thin piece of clear acrylic. I should finish this project by this weekend.

I do plan to offer this project though the Pattern Depot.

[henry1]

That would be great for my grandaughte,r thank god for cheo hospital in Ottawa saved her , you see she had cancer at 3 yr old now she is 12 yrs old but still regular check up for not the cancer to come back

[fwharris]

Cool project and sure she will love it.. I should get some takers for the project!!! Great job!

[badbert]

Very cool!

[easybuilt]

That is so awesome!

[guido5286]

Nice. I have a suggestion though. You were talking about buying the mirror on eBay. Could you not buy a cheap pane of glass and paint one side black?

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[DickB]

Nice. I have a suggestion though. You were talking about buying the mirror on eBay. Could you not buy a cheap pane of glass and paint one side black?

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No. The box uses a special front-surface mirror. The reflective coating is on the front, not on the back like a regular mirror. If you use a regular mirror, you will see a gap - the glass - between the back of the mirror and the slot into which the mirror is placed, spoiling the effect. Only with a front-surface mirror will the sides of the box appear to be seamless. Take a look at this: http://en.wikipedia.org/wiki/File:Specchi.jpg

T (http://en.wikipedia.org/wiki/File:Specchi.jpg)here are some DIY instructions for stripping the coating from the back of a regular mirror to expose the silver, then reversing the mirror, but I haven't tried that.

[Smoken D]

Very Nice and Well Done. A lot of thought went into this project. She will love it!

[lawrence]

awesome! This is one time that "thinking inside the box" is really "thinking outside the box!"

Lawrence

[Bigtyme]

Very nice project DickB. I am sure your granddaughter will love it and I think a number of will too when it comes up on the Patten Depot :)

[DickB]

Very Nice and Well Done. A lot of thought went into this project. She will love it!
Thanks. It seems deceptively simple at first, but of course the devil is in the details. Figuring out all the dimensions to get the right angles and to get everything to fit properly, plus make it not so difficult to build, does take a lot of planning and trial and error, at least in Designer. I find myself designing one part, then the next, then mentally looking at how they will fit, then going back to make changes. But in this case I haven't had to cut and then discard a lot of parts to get everything to fit.

[DickB]

Finished. Look closely - can you see that there is a mirror in there?

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[bergerud]

Not I. It looks pretty good to me. Is or is there going to be a glass in front to keep the little finger prints off of the mirror?

[badbert]

Nope! I sure can't! It looks great! I want one now! LOL

[DickB]

Not I. It looks pretty good to me. Is or is there going to be a glass in front to keep the little finger prints off of the mirror?
There actually is a 1/8" clear acrylic pane in front.

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[DickB]

I'm working on the project manual now. Hope to get it into the PatternDepot soon.

[Capt Bruce]

That's going to be a popular project Dick if we can get the special mirror without too much difficulty. Many thanks for designing this.

[henry1]

that is nice don't see no mirrow

[DickB]

That's going to be a popular project Dick if we can get the special mirror without too much difficulty. Many thanks for designing this.
They are readily available, but not always inexpensive. They are used with lasers and in kaleidoscopes and there are supply outfits for both. I will include sources in the manual. www.firstsurfacemirror.com (http://www.firstsurfacemirror.com/) will cut one to spec but it will cost $20 plus (I presume) shipping. A better option might be an acrylic mirror such as from www.bostoncraftworks.com (http://www.bostoncraftworks.com/FrontSurface.htm). They have a 17" x 13" A 2mm thick acrylic front surface mirror for $17.95 that would be easy to cut on a table saw or the like (that is how I cut my acrylic widow). They also have a thin 12" x 12" sheet for $9.95 that can be cut with a scissors. Acrylic is a good idea in case the bank gets dropped, and I suspect the optical qualities would be fine for this project. The project file is set up for a 1/8" thick mirror, but a thinner one will work fine if the mirror backing board is glued to avoid movement, or the file could be altered.

[DickB]

Hmm - maybe I should by some acrylic mirror and clear sheet, cut the mirror and window to the sizes needed, and offer the pair for sale on my web site. It would be cheaper for those making only one or two banks. These could easily be sent by Priority Mail in the US for $5.

[mtylerfl]

Super-cool project! Will be a very popular store item, I'm sure!

[Capt Bruce]

Thanks for the source information and for considering being a supplier of the mirror and window materials to make a total kit. I think you have a winner here.

[DickB]

The more I think about this, the more an acrylic mirror makes sense for this project. It will also simplify construction a bit and allow a bit better-proportioned front. I have acrylic mirror stock on order and will be offering the cut acrylic as a kit. So I will be holding off making this available until I get this sorted. Sure glad I'm not on a POM schedule!

[DickB]

Dusting off an old project and an old thread, this is my latest iteration of the Magic Coin Bank. Yes, it has been quite a long time since I first worked on this project. I did switch to using an acrylic front-surface mirror, made the window larger, and changed the way the the acrylic window is installed making it easier to build. I'm bringing this one to the conference show and tell.

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I've recently moved and have yet to establish my shop, which is going to take some time as I need to have one built. I do intend to make this available as a project and offer the acrylic window and front-surface mirror as a kit, but realistically it will be several months.

[Bigtyme]

Very cool, Dick. Looking forward to seeing this as a project. Great gift for young ones....

[zan29]

Very nice indeed Dick!