Good News now that Winter DIY camping trailer build project session is getting started.
After a long unavailability, the HarborFreight #62647 4’x8′ Trailer Frame Kits are back in stock! For many home-built camping trailers this is the go to bolt-together frame people use as a base. It is easily modified to a shorter 4’x6’ and other configurations depending on your needs.
From my experience they work well for camping trailers that will see pavement and occasional well maintained off-pavement towing with little to no modifications. For folks planning light duty off-pavement towing, what I would refer to as Soft Roading, I recommend making some upgrades. Here is a Tventuring thread on the topic of How-to enhance a Harbor Freight frame for use under a DIY Camping Trailer.