Step-by-step guide on how to build a tactile overlay for an AAC device

Last month we had a great switch repair/teardown from very wonderful Kate McCallum, who is someone I take very seriously and who regularly fills Twitter with useful and interesting bits of AAC hackery. Kate is an SLT technician from Beaumont College and this month she’s giving us an awesome step-by-step guide on how to build a tactile overlay for an AAC device.

I have a person who needs AAC –  they have significant physical and learning disabilities and CVI (Cortical visual impairment  –  a form of visual impairment that is caused by a brain problem rather than an eye problem). Auditory scanning is unsuitable for this user.

So this is what I did:

Screen Shot 2014-07-26 at 20.05.42

(click for full size – it’s quite difficult to make out the detail otherwise)

In this post I’m going to take you though the process I used to build it and talk a little bit about the things to keep in mind during the process.

Step 1: Gather your parts

I found one of these in the cupboard and pulled it apart. Screen Shot 2014-07-26 at 20.11.17

Screen Shot 2014-07-26 at 20.11.36

I also grab my box of tactile bits:

Screen Shot 2014-07-26 at 20.13.21

Step 2: construction

I print off an overlay and laminate it using mat laminate.  I’ve found things stick better to matt laminate and it also helps to scratch the surface with sandpaper.   Where possible I choose significant objects. e.g I use a cut down drinking straw for drink and an apron string for food.

Everything is different so be prepared to attach them in different ways: I stick with with a two part adhesive (MitreBond in this case), sew them on thin wire or cut the laminate and thread the items though: here’s a selection of the different approaches.

When they are all done you get a lovely selection like this:Screen Shot 2014-07-26 at 20.13.48

Screen Shot 2014-07-26 at 20.13.31

Step 3: Putting it all together and case modding

Lots more to do yet! I stick the tiles to the back of the keyguard with tape and screw it back into place.

Screen Shot 2014-07-26 at 20.14.29

Velcro has a great tactile feel but it’s painful if you hit it or rest of it.  To prevent injury I made this key deeper using adhesive foam around the edge of the cell.

Screen Shot 2014-07-26 at 20.14.37

 Our user  is learning where the different words are stored/located. To assist physical access issues, I have blocked off some of the cells. I did this with the caps until I ran out, then used laminated black card taped in place for the remaining section. Screen Shot 2014-07-26 at 20.14.55

Some quick tips that didn’t fit in above:

  • Soft squishy fabric does not work brilliantly; the squishiness gives and makes it difficult to press.
  • Keep the backs of the tiles as flat and smooth as possible to prevent unwanted activation of a cell. Equally, try to make tiles from things that don’t stick up too much to prevent accidental hits.
  • Once you have established a position for the cell don’t move it. For a person with CVI consistency is key. The same is true for the communication aid, make sure it’s always positioned in the right place.


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