My oldest telescope Meade ETX-125 focuser modification project (published a decade ago on Instructables):
In addition to improving the smoothness of the focuser motion, this mod allows setting the scope into a perfect focus by dialing a value from the list of settings for each of my eyepieces and camera backs. That's also helpful for arranging exposures with the rear mounted camera while tuning the perfect focal position from test shots' analysis. See it in full details on the Instructables website.
DIY Newtonian OTA collimation 3D Print Eyepiece Zhumell camping chair reference transport AstroScan ETX-125 FOV Focuser alignment car cradle laser mirror plywood AFOV Astromist DSO Electronics Photography apperture collimator diameter finder green laser handle telescope telrad tips weight Adaptor Barlow Celestron Clockdrive GSSP Imaging PDA Photoshop Refractor Specs Televue Wide Field Windows about balance ball carry catalog cleaning counterweight dark adaptation dew dob finderscope focal gain goto haul heavy height hoping hopping length limit magnet magnitude map motion mount objects list observing phone ratio red dot resolution simple size sky spherical star test tracking travel zoom