TELESCOPE MAKING by Jerry Oltion Here's a lightweight reflector that fits in your carry-on luggage. I live in a forest. The only view of the sky I get from my house is a tiny notch above my roof, viewable from my driveway. To make matters worse, my sky is badly light polluted. So every telescope I've made has to fit into my car for the drive out of town and be at least tolerably easy to set up and take down in the dark. I also dream of traveling to the Southern Hemisphere to see the part of the sky inaccessible from my home latitude of 44° north. Somehow, I don't think I'll be taking my 12½-inch binocular scope on an airplane, though. Nor do I trust baggage handlers with a classic Dobsonian or even a refractor in a padded case. What I need is a scope with enough aperture to be useful that packs into a box I can carry onboard. A Seed Is Planted In my October 2016 Astronomer's Workbench column I wrote about an amazing travelscope built by Dutch telescope maker Roel Weijenberg. It sported an 8-inch f/4 mirror yet fit into a box only 9.25″ × 10.5″ × 3.9″ on a side - a box made up of the scope's own ground board and rocker box. The moment I saw it I knew I wanted to build one myself, but it took me several years to do it. Why so long? I had to work up my courage! So many elements had to fit perfectly with so many others that the entire process seemed fraught with peril. I eventually set to work and kept track of the many design decisions I had to make along the way. It's those decisions, many of which apply to any telescope-making project, that I want to share with you now. It's my hope that this story will demonstrate how a methodical approach to telescope making can see you Building an Ultra-portable Dobsonian BIG AND LIGHT The assembled 9½inch, airline-compatible travelscope awaits dusk on a mountaintop. 60 APRIL 2022 * SKY & TELESCOPE