Above is a video detailing one method for populating a two sided surface mount PCB. We covered using ... as well as a question about how two sided boards are populated. This was a good question ...

Double-sided mounting tape is a DIY essential, so you'll want to pick the best one for your project. These are the two strongest options based on reviews.

A small square of double-sided copper-clad board is used as a base. The body of the crystal oscillator is mounted on one side of this base. On the other side there is a mosfet and a thermister.