Primers of the V3-V4 region

How can I design primers of my V3-V4 region concurrently? I am a bit confused where would I get the primer sequence of both regions combined?
@pschloss

I strongly discourage the use of anything but the V4 region. For reasons why, you can start here:

I’d gently add, that if you don’t know how to design primers, then you really should stick with the V4 region.

For those who insist on using something other than V4, then this post about customizing the references is important…

Pat