After my first attempt of creating a basic tablet with the Raspberry Pi, I wanted something that was a bit more robust and useful for my children. Initially designed to have a built in thumbstick and small arcade buttons, the design has been modified throughout the build phase. The finish is described by my wife as 'organic' :-) It is not perfect by any stretch of the imagination, but I am ok with that, because I really enjoyed this build.
The decision to create something in fiberglass was because I wanted to create something exactly what I had in my mind. Having not used fiberglass before, and never having made a mold, it was a chance to do something new and different. I have entered this in the competition, if you like it, please click 'vote' at the top right. If you hate it... have pity, and vote for me anyway :-D Maybe with a new dremel, my next 'ible will be better.
The case is deliberately fairly spacious. When creating the previous type of pi tablet, the hard part was fitting everything in. Endless squashing things together when closing it, always disconnected a cable or connection and I would have to dismantle it again to get something working. Especially as the screen connection for the official 7" screen is a bit flaky and not very solid. So this version was going to be very spacious and easy to have everything inside.
I thought about getting the design 3d printed, but I enjoy the fun of doing this sort of thing manually and have not used much 3d software. The construction phase is what I like, actually playing with the finished product I leave to my wife and kids. My children will be using this to enjoy the games I played as a kid.
To create a case that was unique and to look exactly how I wanted it to be, I decided to form a model from expanded foam insulation. Having seen a lot of youtube videos on creating a mold from a blank or plug, it seemed like the best way to go. However, in practice I changed the method. I started covering the foam in car body filler, but then when I wanted to change it slightly, it made a lot of dusty mess.
I had seen some people using Plasticine to build blanks, and then create a silicone mold. So I chose to do a little of both. Keeping the basic foam shape, I used plasticine on top of the foam to create the shape and finish that I wanted. It was very easy and allowed me to get a smooth finish very quickly. I knew there would be a bit of finishing work on the final cast, but I was ok with that as I was expecting to have to change things as the build progressed anyway.
Plus, using a mold process was repeatable, if I wanted to make more (I have 3 children, making only one of anything is rarely an option), then it would be a simple operation of creating another cast from the mold.
Next, on to the build..
Step 1: Connect Everything
I started by checking what space I would need in the case.
Screen - Official 7" touchscreen for Pi
Speakers - Amazon.es
Battery pack from a 15,000 mAh mobile charger, I also kept the controller circuit to charge my phone from the usb sockets on the side of the case.
Small arcade buttons
I tested the set up completely, choosing Retropie over Piplay simply because I wanted an easy way to run Kodi with the gamepad. With the current set up, I can easily play games, and can play movies or TV shows with the same controller.
The gamepad that I started with cost only a few euros on Amazon, and after using it only a few times, it stopped working. For 9 euros I purchased a set of two, which I am much happier with. They are more colourful and feel much better to use. Plus there are two of them, so I can run two player games.
You can see that originally I managed to keep the batteries together, but when placing them in the case it seemed much more ergonomic to have the weight balanced between two hands so you can see them separated in the second photo. In a later step you can see that they are split in to the case on either side. The battery life is great. I can easily have this running all day long.
When I came to the final version of the software, I used the standalone version of Retropie. I transferred the roms with filezilla on port 22 (ssh), and spent some time fiddling to get the gamepad to work. The mame set up is different than the other emulators, so it is a bit finicky. I also went in to the alsa-config and cranked up the volume output, and disabled the dither for audio output.
In the next section, I start with the case build...
Step 2: Building the Case - the Blank
Initially the plan was to create a case that had a thumbstick and arcade buttons, but when I could not find a decent sized joystick or thumbstick on amazon.es, I thought that it would be a better idea to just encompass a gamepad. It would certainly be cheaper, and when my kids were playing two player games, player one could step back from the screen and not interfere with the view of player two.
After watching some YT videos on how to make a part in fiberglass, I realised that the most effective way to do this was to make a blank or plug, and make a mold from it. Because the whole thing was on a very tight budget, I did not use as much fiberglass as I should have done in places. Plus if I had unlimited budget, I would have made a silicone mold, not a fiberglass one. This method worked out ok though.
So I started with some expanded polystyrene (the first image), but it was too weak and not that easy to get a smooth finish. Then I found that the foam insulation was really super cheap for a big sheet at the local DIY shop. So i switched to using it.
I started to cover it in car body filler, but noticing very quickly that it was expensive and makes a lot of mess when shaping it, I switched to using Plasticine. This was super quick and simple. In one night I had a finished shape that I was happy with. Originally I planned to leave the holes for the speakers, but it made more sense to cut them out at a later stage.
Finally, I laid down some card and tape around the halfway point to start making the mold, and covered one half in quick set epoxy that I had lying around from a previous job.The reason for doing this was that I read somewhere that some modeling clay can interfere with the curing process of some resins. So a barrier of epoxy was a method of stopping this. Also, in 15 minutes, I had changed the soft mold, in to something that was hard and i could work with easily without putting thumb prints in the soft clay.
Next, making the mold..
Step 3: Building the Case - the Mold
Starting with the most difficult side, I started laying down fiberglass.
It was clear from watching the YT videos on how to make a mold, that this would need to be a two part mold design. there were just too many curves and corners to make a single mold. If I did not do this, i would not have been able to get the final piece out of the mold.
Around the speakers are some compound curves too, and I had to have the halfway point of the mold at an angle.
Initially I tried to mix up my own gelcoat, by mixing some car body filler paste, with raw resin to make it a little thicker. It worked ok and i painted it on with a brush around the difficult areas.
I had quite a few issues with the fiberglass too. Initially, the only place I could find fiberglass matt was in the DIY shop here (Leroy Merlin). It looked very thick and I had hoped that I would be able to see the pattern of the matting in the final build. However, I did not realise that this thicker glass fabric matt was actually what they use to do roofing repairs here in Spain. It would not bend around the shape of the mold and in places, I ended up laying down individual strands (yes, it was that thick!).
I then bought some pre-made fiberglass paste from the supermarket car section. Quite expensive again, it was actually much easier to work with and i used it for the rear of the case.
I left out a big hole at the rear of the case as my plan was to leave a large hole to insert all of the components, and have a screw on plate at the back. A nice bit of carbon fiber is what was in my mind, but I found out that is also pretty expensive. :-) Currently i have just a square sheet of pvc covering the back.
Time to crack open the mold...
Step 4: Opening the Mold
Opening the mold was easier than I thought, and because I had covered the whole thing in plasticine, it was really simple to open the mold and clean out.
I looked online for 'mold release' and they were all pretty expensive. I was looking for something that I could use for a few euros.
Deciding to buy some car wax from the supermarket, I would double up on the types of mold release. Hair spray was mentioned as a good DIY mold release, that with the wax and I was sure I would have enough.
It turned out that car wax, unless you buy the proper expensive stuff, is not a good option. It seems that all car wax, scratch remover and all those similar products are made using an air drying resin. In fact when I added it to the mold, it made the mold feel tacky. So i rubbed it all off and let it dry in the sun.
I looked to see if I had any vaseline, which I thought we would have somewhere, I had read that it was also a good DIY mold release, but I did not have any of that either. I did find a couple of cheap lip-salve sticks that someone had given to my kids years ago, and so i used some of that to coat the mold. It also smelled of cherry, which was a welcome relief than the resin smell. :-)
Next, time to start laying down the fiberglass...
Step 5: The Final Cast..
Now that the mold was covered in a mold release, it was time to start making the mold.
I did one side at a time, staying away from the edges. Then clamped the two sides of the mold together, and reached through the hole in the back and worked on the join.
I did not take many pictures of the process of filling the mold. It was a messy process that always ended up covering my hands in resin. Even if I started out wearing gloves, I still got sticky.
A couple of things to mention here. I did not have much in the way of materials and ran out of resin a couple of times. (The pots were pretty small and I only bought them one at a time. I used about 3 for the whole build). Because of this, I missed a few spots. I wanted to keep it lightweight with only one layer of fiberglass, but missing entire areas was not planned. :-)
It came out of the mold so much easier than I expected. It was not really smooth at all and I was fine with that. getting it to a nice finish would be done later. In fact I have still not finished that because there are some places that need fine filling.
The part at the front between the front edge and the sunken area for the controller, I missed almost completely as I could not see it or work on it. Making a 3 part mold would have been better. It did need a bit of work after it came out of the mold.
As you can see from the last picture, I also changed the way that I wanted to mount the screen. So i went back and added some fiberglass around the screen area. Fitting the screen on the plasticine would have been better, because I would not have needed the sugru rubber edge for the screen. Still, next time. :-)
Adding a layer of primer, also allowed me to see the imperfections, for filling and sanding.
Next.. time to test fit the components and paint it....
Step 6: Painting and Adding the Guts..
The original plan was to keep the plastic surround that I had on the screen, but when I saw that it would be a lot easier to mount it by removing it, and having the glass on one side of the cover, and retaining the screen from behind, that became the new plan.
I used sugru to make a seal between where the glass would sit on the front, and the case. It has a lip that the glass drops in to, so it protects the screen when upside-down. I used red sugru, as I expected the paint to chip off the rubber eventually.
At the top I mounted the small amplifier that I got from amazon. I got a lot of hiss from the 3.5mm jack on the Pi2 and it was recommended to use an amp, so this is what i did. It is nice, it gives a great sound and runs from the same 5v supply as the rest of the components.
The speakers were also from amazon and they are just hot-glued at the rear.
I would like to have used a wireless gamepad but they are pretty expensive, so I just made a small hole in the case and ran the cable through to the pi. A bluetooth gamepad has been added to my 'future upgrades' list :-)
The batteries were split across the different sides for even weight distribution. I did not want to mess around with them too much, but I am happy with the result of tucking them away.
The charging circuit for the batteries was also mounted to the side of the case. I originally mounted it to the front, but I didn't like the screws being visible, so changed it to the back. It allows me to charge things like my mobile phone, and also to charge up the batteries.
The switches at the top control the power from the batteries to the pi, amp, and screen. The second button is the 'on' function for the battery pack. If you press it twice, you get a little LED torch that shines out of the side. I am not sure I will be using that much.
Next, the final result and thoughts...
Step 7: The Final Result and What I Learned
It runs nicely, it took a few hours of faffing to get the software running well. The Retropie controller set up is not simple at all. It sort of is when you know how, but there has been so many changes to the software over the last 12 months that most of the instructional videos on YT are out of date and send you down the wrong path. That being said, I did not pay for the software and for community based freeware, it is phenomenal.
Kodi runs nicely but I noticed that unless you install Kodi natively, it cannot see the base partitions and you have to be mindful of where you add the media. It will not see a USB drive added to the pi, but media files need to be within the /home/pi folder. I suppose you could symlink it, but I do not need a solution that much to warrant the time it will take to work on that.
What I learned:
I learned from this process that even when I try to be patient, the impatient 'gotta-see-what-this-looks-like devil' is always present on my shoulder. Being it opening the mold, slapping on the paint, or putting all the stuff in before I have finished the case was a constant source of excitement. Also, batteries should always be fitted last... and metal bolts and batteries don't mix well. I had to replace a few cables as a small short circuit melted the wires during a trial fixing.
Molding things with plasticine and fiberglass is actually a lot simpler than I expected. It is messy, time consuming and gives off deadly gasses, but with a half hour every night for a couple of weeks, anything is possible.
Molding with clay or plasticine is best done with a light colour. White or black is no good as you cannot see shadows. I used a red colour for the rear part and it was so much better. I think other modelers know this already, it was new for me.
I also should have worked out exactly how to mount the screen before making the mold. I had an idea that I would work it out when the time came, but actually, pressing the glass edge of the screen in to the clay would have made it super easy to have a flush screen fixing as part of the original mold.
A usb extension from the pi to an external socket - for two players or adding my wifi for updates.
An RJ45 extension and socket to the case, so i do not have to open the pi.
A way of adding headphones.
I would also like to add a cloth or rubber base to the controller 'hole' and add some magnets that will hold the gamepad in place. I will take my time over this and use the broken controller to work out the best place to have them mounted.
Ditch the cables and have two bluetooth controllers :-)
I hope you enjoyed this instructable. It is the community of people like you, reading this, that keeps us energised to make things. Thank you for reading all of this. If you like it, please vote for me (top right).
Thanks to my brother for giving me the Pi2 and screen :-) I hope I make you proud. :-)