Lots of things are possible to develop, like computers themselves. Whether it would be practicable to do this with the resources at your disposal may be another matter.
Generally items like modems that are mass-produced using dedicated ICs are not easy to replicate at home. High-frequency operation as seen in wireless devices makes for greater difficulties. Since these items are difficult to make, but available commercially at fairly low cost, I would say that they do not make very good home projects.