I wasn't familiar with that company so googled some 870's they have done. Looks to me like magpul furniture, mag extensions with a railed clamp, and two machined cuts in a factory bolt with a gold finish applied. The rest is just paint and fancy photography. You could get Casey at Tac-Ord to do all of that except that gold finish on the bolt. You can buy the parts from S&J hardware or other places in Canada.
No idea what purpose lightening cuts on a pump action bolt serves, but it sure as poop looks cool.