I made this backpack for a client for a last minute prop, I had to use what I had lying around that wouldn't take a lot of time to put together. The end result was pretty cheap and pretty easy and I thought I'd share since I didn't see a lot of people who've attempted this.

Supplies

Supplies:

4mm Eva foam

Eva foam dowels 5mm (2 packages)

2 1 liter soda bottles

colored satin cord

Exacto knife/utility knife

Contact cement

spray paint

Plastidip (white spray)

Velcro strips

hot glue/hot glue gun

dremel (optional)

wood glue

small items for buttons

.nylon straps

Step 1: Step 1: Make a Box

I started with a 5 sided box, leaving one side open so I could attach a rig and straps later. I decided on the size based on the person wearing it but I made 10" by 10" perfect squares. I measured and marked with a sharpie (always shows up on eva foam) and used an exacto to cut the pieces. I used contact cement to glue the pieces together, I put it in a little squeeze bottle and it's SO MUCH EASIER to manage. Line up your edges as best you can.

I also use a heat gun on the cement a little before sticking, it accelerates the drying process so it sticks faster.

I repeated this step for the trapezoidal shaped boxes on the sides. I used paper to first draw out the design to make sure it would work and fit- then cut it out and glued it the same way as above.

So you should have three separate pieces, DO NOT ATTACH THEM.

Step 2: Step 2: Turn Your Soda Bottles Into Electrical Conductors!

Take your 2 soda bottles and cut off the bottoms. I measured the bottle into 3 sections and used contact cement to glue the dowels over the drawn lines. DO NOT USE HOT GLUE, it will warp the bottle and ruin it (learned my lesson).

I created 2 new bottoms by cutting larger circles out of EVA foam and heating them over a ceramic bowl. Once it was rounded enough I placed it on the edge of my bottle, marked and cut off the excess. I glued the eva foam dome on the bottle then glued a dowel over the edges to create a more smooth connection.

Then I measured the center of my trapezoidal box and cut a hole a little smaller than the bottle spout. This way I could shove the bottle through the hole and glue it in there, which we'll do later.

Repeat for other side

Step 3: Step 3: Add Buttons and Prep Edges

Optional: I took my Dremel and went around the edges to smooth them out.

I then took wood glue and painted it just over the edges, this just helps fill in any cracks for final sealing. If you want you can paint the whole thing, it seems to help Plastidip go on a lot smoother.

I used a bunch of weird stuff for my buttons, domed buttons, drawstring cord edge thingies, plastic large grommets, I got creative. I even used an empty candy box to raise one of the buttons. Not super accurate but got the job done. I just hot glued these down.

When the wood glue is dry you can run some sandpaper over it to get out any runs or drips.

Step 4: Step 4: Prime and Seal

I sprayed everything with plastidip, when you use plastdip it's not like spray paint, you spray a generous coat on until the whole thing looks wet, make sure it's not too much because it runs.

Wait for it to dry and do a second coat. I haven't attached my bottles yet, we'll do that after painting.

Step 5: Step 5: Paint

I used spray paint and masking tape. I painted under where the cord was going so I wouldn't have to use as much. I did the Twitch Prime version which is all yellow and blue and silver.

Do it outside or wear a mask for fumes.

Step 6: Step 6: Compete Pieces and Start the Rigging

This is where you glue the bottles in. I used a ton of hot glue to really just melt the plastic and foam together. It worked just fine. I put it on some stuff that would keep it straight while the glue dried, otherwise it looks a little off kilter.

Now you have three pieces, the center block and two bottle with the trapezoids.

This is super light, so I used a velcro system to attach these three pieces together, made it easier to ship, pack and adjust. It's basically 4 strips of velcro. 4 are hot glued to the inside of the trapezoid shape. Then line up the trapezoid where you want to to sit on the box and mark the velcro strips. You will take your exacto and cut slits in the box for the velcro to go through.

On the inside of the cube box, glue the opposing velcro pieces under the slits. So all you have to do is pull the strips though and secure them on the side of the box, and all pieces come together.

So you'll need 4 strips for each box. I tried contact cement and the hot glue worked better.

Step 7: Step 7: Add Cording and Backpack Straps.

I used colored satin cording and wrapped it around the bottles to create the illusion of wire.

I then just used nylon webbing straps to create back pack straps hot glued into the main cube box. The back of the cube box is still open, but that makes it easier to attach everything. You could always put a backing on and magnet it on there or something, if you wanted.

There you go! It was pretty fun. Of course I would spend a little more time on it next time, but the client loved it and it worked for a fun romp through the con floor.

Happy Crafting!