Has anybody built their own bumper for a 2nd gen?

Start with your tools and skillset. Can you weld? Have a bender? Tube notcher? Ever fabricated anything before?

After that, consider how your truck gets used. Will it mainly be a cosmetic thing for on-road duty? Do you rock crawl? Bash through the desert?

What shortcomings have you hit with the stock bumper that you'd like to overcome? Appearance? Approach angle? Strength? Winch mount?

Have you seen any other bumpers that you like, either for functionality or appearance? Perhaps a combination of several different designs?

Are you alright with the bumper possibly affecting airbag deployment?

That will give you an idea of whether it's a do-it-yourself or something that you'll pay a fabricator to build. You'll also have a design idea and a list of requirements. Definitely a good place to start.