Wisconsin Professional Stamps. Our pre-Inked stamps are made with the latest technology. These do not require a stamp pad, are compact, and have fewer moving parts; compared to a self-inking stamp. Pre-inking stamps are made with porous die infused with oil-based ink. They will last for thousands of impressions and are easily re-inked. Ink options can be found under Ink, Pads, Etc. category.