His shop in Philadelphia was called "Sign of the Golden Eagle." In those days most shops were called something along those lines because of the signs they hung outside their shops. His shop was in the neighborhood of Third and Chestnut street.
Randolph was a cabinet maker. He also made coffins, picture frames, Chippendale furniture, etc. He also made the desk that the Declaration of Independance was written on. Thos. Jefferson and George Washington often stayed at the Randolph home while on business in Philla. during the 1st Continental Congress.
Randolph was a staunch patriot, and was a secret agent for Washington, as well as a commander of the Philladelpha Light Horse. He took part in the battles of Princeton and Trenton, and was a guide for Washington's army in the night march from Princeton to Trenton. (Randolph had grown up in Princeton and knew the area quite well.)
He was also pretty kind. Around 1777, workers at Speedwell captured two deserters from Anthony Wayne's corps from Mount Holly. He asked for a pardon for the "unlucky fellows" and "desire[d] no expense of mine be charged to the country." What was at Speedwell then? There was a "good new two story house, framed and covered in cedar, good cellars walled up by stone, good brick hearths, and oven." There was also a log house for a sawyer, barn and stables for 16-18 horses, and a sawmill with "two saws, newly repaired." He also held two hundred acres of iron ore.
Randolph bought Speedwell around the 1760, to build a sawmill to provide his shop in Phila. with lumber. After he sold his shop in Philly, he became a merchant, and became quite wealthy. Three times he tried to sell the Speedwell property. Each time the new owner defaulted and he regained ownership. In the 1780s, he built the furnace there. He also built another large dwelling house at Speedwell, although he himself was also living in Burlington.
In 1791 he died, but his widow leased the works out to various people while she lived in Morristown. In 1833 his widow sold the property to Samuel Richards, who then sold it to Joseph McCambridge, owner of the Eagle Tavern in 1850, who then resold it to Stephen Lee in 1868.
I am late for work now, but I will most likely end up writing a more detailed history in an article for the site in the next few weeks.