Those silhouettes are generic, possibly even royalty free, graphics that can be used in non-Nintendo produced products. For example, they're also on the Hori Amiibo carry case: http://www.amazon.co.uk/Amiibo-Trio-Case-Nintendo-Wii/dp/B00QGMA650/ref=sr_1_2?ie=UTF8&qid=1436083389&sr=8-2&keywords=hori+amiibo+case
http://www.amazon.com/HORI-Amiibo-Trio-Case-Wii-nintendo/dp/B00QGMA650
During PAXeast I used this to carry my amiibo, it fit inside my small messenger bag with ease. It was great fun being able to use amiibo in the console free play lounge, especially seeing random passerby's challenge my Villager amiibo.
I have the Hori Trio Case. At the moment I have 8 amiibo and can fit all of them in there without any issues and room to spare =)
http://www.amazon.com/HORI-Amiibo-Trio-Case-Wii-nintendo/dp/B00QGMA650
Also on sale on Amazon.com ($3.11 off retail), but slightly different style
I don't know anyone who would bother buying carry cases.
http://www.amazon.com/HORI-Amiibo-Trio-Case-Wii-nintendo/dp/B00QGMA650
They're also on the US version of the case.
Yeah, there's definitely a little wiggle room for them to sneak around under while in the case if it gets tossed around enough.
I plan on getting the blue one that Best Buy has that holds twelve for storage at some point, hopefully it'll go on sale again. I also ordered this case from Amazon when it was $12.99 about a week ago for taking just a few amiibo on the go. It only holds three, but it looks a little more secure since there's just less room for them to toss around in. I can't tell, but the dividers on that one might be velcro, too.