Here in the UK, we use metric fasteners. When you go shopping for small screws though, the only sizes you can generally get below M3 are old, awkward imperial sizes. Even if you are happy with M3, the variety of shapes and lengths is woefully inadequate. Imagine my delight when I found perfect screws on Amazon of all places.
Apparently widely available in Japan are metric screws with very shallow heads. These are ideal for many tasks in small robots but almost impossible to find here. Not so easy in the USA either I believe. After taking out a laptop hard drive, I realised that the screws holding the drive into the carrier were exactly what I wanted. Out of curiosity, I looked in Amazon for “laptop screws” and came across these:
They sell a pack of 156 screws of exactly the type I wanted in M2, M2.5 and M3 in a variety of lengths. Their entire range covers nearly everything I need. Excellent!