My recommendation is to focus on building communities of candidates who have the requisite technical skills for many of your core jobs. Here are some steps in the process:
1. Identify these potential candidates by using a website such as LinkedIn
2. Attempt to link in with each candidate by sending an In-mail that is crafted not to attempt to recruit them for a current opening but asking them to join one or more of your various communities
3. For those that join a community, send them a monthly e-newsletter that you craft. The e-newsletter should highlight key happenings at your company such as new product launches and testimonials from current employees on what it is like to work at your company.
4. Within the e-newsletter, don’t forget to include a link to your current openings and also a link that allows someone else to sign up for your e-newsletter (in case, the e-newsletter is passed on).
By following these steps, your ability to find candidates for your hard-to-fill jobs should great improved.