Step 1: Design your box
Step 2: Materials and Tools
Here are the materials and tools I used
Foam core sheets - (the kind you might use for a sign or display) Get the largest size you can. I used two large sheets
Fabric - Pick the fabric and ribbon you plan on using to cover the box. You should only need about a yard.
3M Super 77 Spray Glue - This stuff is awesome. It will stick a variety of materials together. Perfect for attaching the fabric to the foam box.
Decorations - I tried a number of other decorations like bows, ribbions, plastic flowers, etc. Add whatever you like.
Large cutting mat - These are great for projects like this, if you dont have one make sure you are doing this on a surface you dont care about.
18"-24" ruler - You most likely will be making cuts longer than 12". Do yourself a favor and buy a $10 metal ruler that is long enough to give you a good clean cut. Having other smaller rulers was also helpful.
Xacto Knife - if you dont have one of these already get one, not a utility knife... and Xacto knife, and buy 10+ blades, you will need them.
Utility knife - This may be necessary to cut through thicker doubled pieces or excess glue later.
Scissors - You will need these to cut and trim the fabric
Hot Glue gun - This is the primary way which you will be connecting the foam core together.
Step 3: Overview
Basically I created 4 separate 5 sided boxes. First, I created the lower and larger box with the bottom and 4 sides. Then I measured and made a lid consisting of a top and 4 sides. I repeated this for a second smaller box.
The picture below shows all four pieces assembled together snugly. Do not glue the lids or the boxes together until the end incase you need to make adjustments or depending on how you choose to decorate them it may be easier to assemble them last. Make the bottoms of the boxes first then re-measure and cut the lids to fit with a 1/16" gap on all sides to account for the fabric.
Step 4: Start Cutting!
Basically, the bottom should be the exact size of your box in terms of the length and width. The side pieces should all be slightly smaller than the exact length and height of the final box because they will be sitting on the bottom piece which will add additional height.
Likewise, two of the boxes sides (the front and the back) will be the full length of the side. The other two will be slightly shorter because of the thickness of the other two sides. If two sides are Length (L) and the material is thickness (T) then two sides must be (L - 2T) The foam core boards I used were slightly under 1/4" This meant I was always cutting off almost 1/4" from the height of all of the sides and nearly 1/2" from the length of two of the side pieces.
Foam core sheets are not very expensive. If you can, roughly lay out your pieces ahead of time to get the most from your material. Using one long cut to cut pieces with similar dimensions means you will have straiter and fewer cuts. You will lose some space due to the material lost with each cut just like wood so measure each cut individually before cutting.
I scored with the ruler 25-50% of the foam then removed the ruler and used more pressure to cut all the way through. This gave me very strait cuts.
Cut only the 5 pieces for each box at a time.
Step 5: Start Gluing
Make sure to test fit all 5 pieces of each box before gluing anything. It helps if you have an extra set of hands since you cant use things like clamps. It also helps if you have a square or an object to align your box with to ensure it is strait when you are gluing.
Start with gluing the bottom to one of the full length sides. Applying hot glue to the paper surface of the bottom always works better than to the foam edge of the side piece. As soon as you apply the glue tilt the side into place and hold it firmly until the hot glue sets. This should only take between a few seconds to and a minute or two.
Once a long side has been set to the bottom grab one of the shorter sides. Apply glue to the bottom piece and to the previously glued side where the shorter side will touch it. You will have to apply the glue quicker this time because you have more ground to cover. Put the short side in place and hold until the glue dries. Make sure everything is flush and square with the bottom and other side.
You will now have a three sided box with one complete corner. Next glue in the second short side. Always glue the second long side last as it does not require an exact fit and can be trimmed later.
Now you should have a completed 5 sided box.
Repeat the same steps for the lid and second box. When constructing the lid make sure make the bottom piece 1/16" larger on all sides to ensure a snug but good fit later when fabric is applied.
Step 6: Cutout the middle
First take the smaller box, remove the lid, and cut into the bottom of the box with the Xacto knife sliding it into the bottom piece flush with the inside of the box. This will leave you with a small ~1/4" frame remaining of the bottom piece that is still glued to the 4 sides.
Take a pencil and ruler and find the center of the larger box's lid by drawing an X from the corners of the box. Measure from the center and draw the footprint of the smaller box. Take the lid off of the smaller box and place it on the center of the lid of the larger box. Use a pencil to trace the inside of the box onto the lid.
Now you should have a square drawn on the large lid that you can cut out. Once you cut it test fit the boxes again to make sure everything lines up.
Step 7: Cut the Card Slot
Now is a great time to test the slot. With the top lid removed and the rest of the box assembled practice inserting a card into the box and see if it gets stuck or jammed. The cards should freely fall to the bottom and lay flat.
Step 8: Add the rear opening
I tried a few different designs and ideas. With foam core sheets you are limited to the type of latches, catches, hinges etc that you can use to make a door or other opening and secure it.
In the end I decided to cut out an opening and have the door swing down on the rear bottom side of the box. I reused the piece I cut from the opening as the door because I needed to leave space for fabric so the fit did not need to be very tight.
First mark and cut out an opening flush with the bottom of the bottom box.
To make a hinge for the back door to pivot on I used Gaffers tape. Duct tape will also work but Gaffers tape is a bit better. I used a piece on the inside and another on the outside. In the pictures you can see the gap between the door and back wall of the box.
Step 9: Cover the box in fabric
Here is what I did.
I took each of the 4 separate boxes and covered them in fabric individually. Then, I used hot glue to assemble them together.
Because I used fabric, I got out the iron and made sure the fabric was wrinkle free as it would be impossible to fix this later. I then cut out a piece of fabric that would wrap around the 4 side walls of the larger box. I used the 3M super 77 spray glue and sprayed both the back of the fabric and the outside of the box with glue.
I placed the fabric on the smooth cutting mat and placed the FRONT of the box in the center and pressed down firmly to stick the fabric to the box. I then stretched the fabric slightly and rotated the box 90 degrees onto one of the sides and stuck that side. I repeated this until all 4 sides were stuck.
If you run into a wrinkle you have a few minutes to work with the 3M 77 so you can pull the fabric up or reposition it if needed. I tried to get my seams to end on a corner or in the rear of the box so they would not show.
You can repeat this process for the other box, the lids are a little different.
For the lids I cut out a square of fabric that was a few inches larger on each side to account for the sides of the lid. I then glued the lid to the center of the fabric and stretched the front and back sides flat. I then moved onto the left and right sides which left me with triangular corners of fabric sticking out at each corner of the lid. For those I used hot glue to stick them to the sides of the box like a wrapped present. I kept wrapping the fabric around the sides of the lid until they were under the bottom edge and around to the inside of the lid before trimming the excess fabric.
You should end up with 4 separate fabric covered box pieces that have neat edges that are trimmed and glued internally. For the card slot opening carefully cut a slit like this >---------< then tuck the excess fabric inside to hide the fraying edges. Cut a large X in the fabric covering the opening on the bottom lid and also tuck the fabric inside. You will need to separately cover the rear door with fabric.
You can now glue your box pieces together to form the final card box shape. Start with the bottom box and apply hot glue quickly to the top edge of all four sides. Before the glue cools carefully lower the lid onto the box making sure it is aligned correctly. You will want to test fit it ahead of time to make sure you left enough of a gap with the fabric for a snug fit.
Next, glue the smaller top box onto the bottom lid taking care to align it squarely with the bottom box. You can renforce the joint between the two boxes with additional glue inside if necessary so dont over do the glue the first time and risk glue showing through on the fabric. Finally glue the top lid on the top box.
Step 10: Decorate and finish
You will also want to create a latch for the rear of the card box to make it easy to open and close the rear door. I tried a number of ideas like using magnets to hold the door shut and none of them worked well. In the end I hot glued a small piece of ribbion to make a pull tab on the top edge of the door. The friction between the door and the back wall of the box between the fabric was more than enough to hold the lid in place. Because of the pattern of the fabric it hid the seems on the door well.
In the end my card box turned out exactly how I had designed it to and worked very well.