Scooter forks are a simple but vital scooter part. The front forks for scooters --(AKA suspension fork)-- needs to sturdily hold the front wheel in suspension in order for the wheels to freely rotate, yet easily pivot with the steering. As such, scooter forks absorb a lot of shock and need to be durable and rigid.
Monster Scooter Parts offer several suspension fork units for Razor E-series scooters, as well as several generic front forks for scooters that will fit several manufacturers' brands and models. These may also work fine for your custom built scooter project.