Recently, Rob Mitchell of Paperclip Robot asked me to try out a new product called BubCap. It's a sticker you place onto your iPhone, iPod or iPad that covers the Home Button, making it harder to click. It's available in three levels of rigidity and does the job well.
Why would you want to do this? There are several compelling use-cases. For example, Paperclip Robot sells many BubCaps to parents who want to prevent toddlers from exiting a certain app and wandering over to Daddy's email account or Mommy's home finance program. The covering material is stiff enough to limit toddler access without hindering adult use.
This isn't a solution for unmanned installations -- you'd want to use a more permanent, lockable device as a theft deterrent -- but the BubCaps are handy for other situations, like classroom or boardroom demos or when paired with assistive software for the disabled.
TUAW tried three solution levels: regular, ultra and max. These are in ascending levels of rigidity. Of these, the regular level most closely approximates the Home Button's native feel. I'd leave that one in place between toddler sessions.
The ultra and max levels made it really hard to hit that Home Key. That's exactly what you want -- a significant challenge for smart-alecks who would get cute with your demos, or someone whose physical development may outpace their wisdom.
The difference between ultra and max is that the max version adds extra rigidity. This makes it a particularly good match to the iPad. The iPad's Home Button well is shallower than the ones on the iPhone and iPod touch, making it easier to press.
The BubCap should prevent most people from clicking the Home Button deliberately or accidentally, which is the entire point of using it.
Each BubCap is a separate sticker. They sell in 4-packs for US$5. In my admittedly limited testing, I found that the caps were easy to apply, came off without leaving residue and were nicely re-usable. Mitchell tells me that the caps can become slightly more sticky over time, but that any residue can be easily wiped off with a cloth.