On Golarion, the role and presence of high tech and magic tech is mostly constrained to one region-Numeria. The Technic League and the Antochian Empire maintain a strong hold on all high tech & magic tech items. This is why the fantastic and futuristic technology hasn't spread far from the region. With the help of the locals' taboos against technology and superstitions associated with it, the League prevents most of these devices from spreading into outlying lands. 

The Antochian Empire restrict all use of their omnimagic to military personnel only. Any items taken out of the region are accounted for and it is strictly against orders to leave any omnimagic items behind even if inoperable. 

You can purchase some technological items in Numerian shops or from merchants, but only a few items will be available. In most circumstances you may only find them as treasure during the course of an adventure. Unless specifically adventuring in the region of Numeria. 

Designing or crafting high tech or magic tech items are done by using the magic item creation guidelines.

Using high tech and magic tech items may require a different set of skill and feats to work with them.