Coin Display Case With Hinged Door

I rarely find myself needing coins on a day to day basis but when I do, it's usually for a specific purpose and a specific coin type. I decided to make a display case that has separate compartments for dimes, pennies, nickels, quarters, and miscellaneous coins. I also have foreign currency that I will definitely be storing in it. Not only did I want it to be practical but I also wanted it to look nice and be something that could sit on the corner of my desk. At first I thought about 3D printing it but I ended up deciding to laser cut it so that I could change the way it looked as I was making it. It ended up being a great refresher into laser cutting methods since bringing life to a 3D object from "2D" components is not always easy.

I used plywood for the main structure and I made the clear window out of acrylic. Later, I decided to add a hinged door to cover the top. After several mistakes (mainly involving the glue), I ended up with a working and a pleasant-looking display.

Materials:

-Small screws

-Wood glue

-Adhesive for acrylic (I used epoxy)

-Paint

-3mm Clear Acrylic sheet

-3mm Plywood sheet

Tools:

-Laser cutter

-Painting supplies

1. brush
2. container
3. painter's tape

-Clamps

-Screwdriver

-Software for vector design

Before any laser cutting can start, an svg file is needed. One can use any kind of vector design software like Illustrator or Inkscape but I decided to use the drawing tool in Inventor which is Autodesk's 3D design software.

I wanted the coins to properly stack on top of one another and not become a jumbled mess, to meet this I decided to make each compartment the diameter of its respective coin. I also wanted to account for variation and assembly error so I measured the coin diameters (or looked them up) and added about 0.01'' to each measurement.

Structure:

1. Back panel- plywood base with solid colored sections which are intentionally 3mm in width. I say solid colored because my thought process was that I could use raster engraving on those sections so that I would know where to but the side dividers
2. Side dividers- section dividers between compartments, back panel is engraved so as to guide how far apart the compartments are they themselves have solid colored sections to guide where the back dividers will go
3. Back dividers- to be placed perpendicular to the side dividers (parallel to the back panel) that ensure the appropriate size based on coin size.
4. Acrylic Window- sized to completely cover the front portion
5. Door- Links (for door hinge) and door panel designed to be wider than the width of the display to for easy opening/closing

I downloaded the drawing from Inventor as a pdf and uploaded it to the laser cutting software which automatically converted it into the needed files. I made sure to have the cutting lines as red and the engraving sections as black.

Everything is of the same material except for the window which I cut separately on acrylic. I made sure to set the correct height and material on the software but I know other laser cutters like glow forge do that automatically.

For laser cutting there is no real way to tell it how deep to engrave, since I wanted a good depth I messed around with the height settings, speed, and had the laser do multiple passes over the engraved areas. Mess with those settings cautiously and at your own discretion, its enough to know where to glue but I wanted them to serve as fitted slider slots.

Steps for assembly

1. Glue the middle and back layers together. Using the engraved portions to guide the side dividers.
2. Glue the back dividers (the panels parallel to the back panel) in between its designated slot and according the engraved portions in order to ensure proper coin space
3. Use a thin bead of epoxy or other acrylic adhesive on the outermost edges of the structure and carefully attach the window to the front
4. Glue the long hinge parts to the sides of the door plate
5. Drill two 1/8'' holes to the top back sides of the structure and attach the smaller hinge parts using screws.
6. Use a screwdriver and two screws to attach the two hinge pieces to each side of the door plate.

I didn't measure exactly where to drill the holes but if you don't want to eyeball it, drill the holes at 4.5mm from the back side and 3mm down from the top of the structure.

Once I made sure the door was working properly, I removed it and prepared the entire structure for painting:

1. Use fine-grit sandpaper all over the plywood surface of the structure
2. Use painters tape to cover the window edges
3. Brush two coats of paint, (I used blue paint)
4. Reattach the door

It’s been a while since I’ve laser cut anything and this project served as a great refresher. It’s a great method for prototyping and I definitely got reminded of many great tricks. Starting with engraving for slots this works really well when the things you are attaching are small. Like raster engraving a 3mm hole for a wooden rod, it allows you to not sacrifice precision by using a drill but it also prevents weak butt joints by having a premade hole that doesn’t penetrate the other side. In the case of this coin display, those engravings worked well as guides but it took a long time for the laser cutter to get them deep enough to serve as sliding slots. I wished that I had instead used the common box joint composed of slot and pin finger joints. Another aspect that gave me great trouble was the gluing of the structure. I wanted it to glue it all at the same time but this resulted in a mess where some parts were falling while the next was being glued. The epoxy can also be seen where it was used in order to attach the window. Next time, I will remember to leave enough time for each part to dry and ensure precision by using clamps as well as using a frame around the edges of the window instead of it being glued directly on top of the structure. Overall, there are things I would change but I’m happy with the structure itself.