Perfect Change Coin Holder

Dec 15, 2015

Thing Apps Enabled

Awesome design! I am oddly overexcited to have solution to dealing with loose coins. I was going to attempt a design, then saw this... minimalist, yet perfect desgn for usability. Turns out US Coins are identical sizes to Canadian, so no need for modifications. Need to figure out how to do another for pennies... Canada quit using them, but still need them in US.

How hard was it to get just the right fit on the coins? I am new to the modeling/CAD and having difficulty finding decent tutorial for fitting parts together. Having this as an example will help get me started. Thanks... love some useful and well designed.

OpenSCAD is free and you should be able to make a penny holder pretty easily.

1) Change the sizes of all the coins to pennies (I measured a penny at D=19.04 T=1.57

2) Press the icon on the app that looks like a cube with an hourglass on the bottom (should be the second button below the rendering)

3) Now the "fun" part, find this part of code and play with the first 2 numbers in the formula (these control X & Y) keep pressing refresh icon to see the changes. the last number affects the opening angle. If you only want 4 pennies delete 2 of the lines.
union(){
CoinCircle(-24.9,14.05,QDia,-64); //Quarter 1
CoinCircle(-24.9,-14.05,QDia,64); //Quarter 2
CoinCircle(24.9,13.1,QDia,-134); //Quarter 3
CoinCircle(23.5,-13.5,NDia,134); //Nickle 1
CoinCircle(0,11.05,DDia,-90); //Dime 1
CoinCircle(0,-11.05,DDia,90); //Dime 2
4) after you render and are happy with the results you can export (you need to render before exporting)

I haven't printed or tested it but the SCAD code might look like this.

Length=85; //Credit Card Size
Width=53; //Credit Card Size
Thickness=2.25; //0.5mm thicker than thickest coin
WallWidth=3.75; //Hub Thickness for flexibimty and strength
\$fn=40;

module CoinHole(Diameter){
translate([0,0,-Thickness/2])cylinder(r1=Diameter0.49,r2=Diameter.51,h=Thickness/2);
translate([0,0,0])cylinder(r1=Diameter0.51,r2=Diameter.49,h=Thickness/2);
cylinder(r=Diameter.49,h=Thickness2,center=true);
}
module OutCoinHole(Diameter){
translate([0,0,-Thickness/2])cylinder(r1=Diameter0.49,r2=Diameter.51,h=Thickness/2);
translate([0,0,0])cylinder(r1=Diameter0.51,r2=Diameter.49,h=Thickness/2);
//cylinder(r=Diameter.49,h=Thickness2,center=true);
}
module CutOut(Size){
translate([-Size,0,-Thickness])cylinder(r=Size,h=Thickness2,\$fn=7,center=false);
}
module CoinCircle(XLoc,YLoc,Diameter,Rot){
difference(){
translate([XLoc,YLoc,0])OutCoinHole(Diameter+WallWidth
2); //Outside Circle
translate([XLoc,YLoc,0])CoinHole(Diameter); //Inside Circle
translate([XLoc,YLoc,0])rotate(a=[0,0,Rot])CutOut(Diameter); //Stress Notch
}
}

intersection(){
union(){
CoinCircle(-12.5,12.5,PDia,-45); //Penny 1
CoinCircle(-12.5,-12.5,PDia,45); //Penny 2
CoinCircle(12.5,12.5,PDia,-135); //Penny 3
CoinCircle(12.5,-12.5,PDia,135); //Penny 4
}
minkowski(){
cube([Length-4,Width-4,Thickness],center=true);
cylinder(r=2,h=Thickness/2,center=true);
}
}

Thank you so much for giving me details I can use to learn the technique and have my useful thing when I am finished. I will post when I have finished.

After straightening coins for a snazzy photo, I realized this would make a unique new baby gift... a collection of coins for the year of birth - so I put my first one of those together too :-)

i actually bought mint sets... one for me, and one for each of my kids for our years of birth... its each coin, uncirculated... i carry mine for good luck and emergency little bit of cash... i've been looking for a way to carry it all without it jingling in my pocket loose.

i think youre dead on, its an awesome gift for a baby, or for anyone really.