Your request says you need to do a combinational circuit (i.e. gates) while your signature says you need to use flip-flops (i.e. sequential). What, exactly, is the requirement of your project (obviously a homework assignment because no one would do this for kicks)?
The most straight forward way would be to use an oscillator: a crystal will have the best stability. A divider (because crystals oscillate way too fast). Some counters (74HC393s), LED display drivers (7447 or similar), and some gates to reset the counters at the right time and increment the other counters.
If it has to be purely combinational, you'll end up making sequential elements out of gates, which would be a nightmare.
j.