New2This,
Welcome to the HS Baseball Web!
The D3 college my son played for a few years ago did hold baseball camps. In the summer they hosted camps which targeted the younger players up through HS age. The coaches were looking to identify prospects among the HS players, although certainly they did not recruit the majority of players who attended the camps.
In the winter I don't think they held a camp because we're in snowy Minnesota and they didn't have an indoor facility which could host games, but the coaches worked at the camp of another area college, so they were still seeing prospects.
Are there some specific D3 schools you are interested in?
Julie