I once used an IR receiver module, and pulsed the laser pointer at ~38kHz. Worked at about 40 feet, but was very tough to get the laser pointed at the receiver module, as it wasn't as bright. At 3 meters, you shouldn't have much trouble lining it up. I used the IR module, because it was for outdoors, and it helps to avoid false triggers. As mentioned above, you could use most any sensors, use a tube to shield out unwanted light sources. There are tons of Laser-tripwire projects on the web, shouldn't be hard to find one that suits you. Mentioned the IR module, as its not something you will find (haven't looked lately though). I used microcontrollers, mostly because I had just started to learn them. A 555 could be used to drive the laser pointer. The IR receiver needs 5 volts (works on a little less), and normally High, if not receiving a signal (in your case, blocked), which works out good for you.
The counter and display, should be easy enough to find on the web, been done for decades. Been using microcontrollers for a few years, and seldom look back...