One option, if using jasper-report is an option for you, would be:
1. Create an image of your pre-printed form
2. Use Jasper-reports to create a report-definition.
- Put you image into the background-section.
- Design the fields "on top" of that background-image
- Run the report with the appropiate data.
3. To integrate the report into apex, you could use https://sourceforge.net/projects/pljrxml2pdf/
This might work also using a different reporting tool.
these materials can help when starting out on jasper though
- Opal-Consulting - Free tools - Jasper Reports Integration
- daust_de :: Oracle XE / APEX: Upgrading the JasperReports libraries to 5.0.1
- JasperReports Tutorial free ebook download
- JasperReportsIntegration 2.0.0 Beta on JBoss 7 : David Ghedini