Quickly clone a microSD card

Since you don't specify an OS, here is the way I'd do it in linux.

plug in the card to your card reader. Mount it (it should mount as any old sdX#) dd if=/dev/sdX# of=/path/to/save/location/image.dd sync=noerror,notrunc bs=1k

This will give you an exact copy of the first 'parition' (if its partitioned.. if not don't worry about it). You can mount these with a local loopback as well to pick files off of the images.

If you are worried about file size, you can alway so something like this page suggests to get it to be smaller and more compact.

Try Macrium Reflect FREE Edition or dd for Windows.