DIY Blast Gate - Dust Collection Tips, Jigs and Fixtures | WoodArchivist.com
Use a wye fitting rather than a tee so that less suck is required to move dust.
Tools: Dust Collection
Dust Collection Plans - by David Grimes @ LumberJocks.com ~ woodworking community
Clear ducting for dust collection system. - brilliant
Adding A Pre-Separator To Your Dust Collection System
Build it Yourself
Miter Saw Dust Collection Hood - Miter Saw Tips, Jigs and Fixtures | WoodArchivist.com
DIY Cyclone Dust Collector - Dust Collection Tips, Jigs and Fixtures | WoodArchivist.com
Rather than a short radius 90 degree turn, incorporate two 45 degree bends with a section of straight pipe in the middle, which will allow the particles to scream right through the turn.
Shop Vac + Dust Deputy + Larger Drum Cart