Make your own dual SIM phone

Anyone tried those dual SIM adapters? Curious about making a single SIM phone dual SIM capable and use then use FreeUp for voice/text and Freedompop for data.

The particular adapter you've linked to does not turn a single-sim phone into a dual-sim. Instead, it enables the use of both a SIM and a uSD card in the hybrid slot of a phone that is already dual-SIM. (The hybrid slot accepts either a 2nd SIM, or a micro-SD card.)
I have also seen posts on other forums about a DYI solution for a hybrid slot, if the SIM and uSD cards face different directions-- dissecting the SIM card to remove the printed circuit from the plastic carrier body, and gluing to the back of the uSD card.

There are dual-SIM adapters that work with single-SIM phones, and include an app that allows switching between the 2 SIMs. I think the result would probably not allow splitting of radios, though, so only one SIM active at a time.