It is often best to have the blower outside (in a weather-protection housing) so all interior extraction parts will be on the blower's inlet side and therefore will have negative internal pressure. That way, any leaks in the exhaust system won't push fumes directly back into the room. It also reduces noise in the room! You might also want to either extend the exhaust out of the blower away from the building more, or raise it up higher, to help disperse odors away from the building and lessen chance of re-infiltration. Then allow for makeup air into the building as far as possible from the exhaust. When a laser job finishes, leave the lid closed with exhaust fan running long enough to ensure at least a complete turnover of air in the machine. Close the machine back up as soon as possible after removing the workpiece(s) because some residual smells can still come from the inside area that was exposed to the smoke/gasses while lasering. Likewise, things like wood and acrylic that you have lasered will continue to give off odor for some time so, if possible, don't leave them lying around in the open...