I used @brota idea but spent time in SketchUp designing something I could use a spare piece of MDF to build to straighten 1/2" Maxline.
Came up with this:
Note that the test plugs are "upside down". The measurements shown are PDC (pretty damn close). If you find its not quite right or you can't drill accurately, you can loosen the bolt and the plug halves can separate slightly and still work. When building, I found a 2' section of RainBird irrigation line for 98 cents that was spot on for outside diameter and used it to set final distance.
It worked well enough, you just have to make sure you don't set the test plugs too close along the center line because they have small ridges on them and will leave small, barely visible indents on the line. I used carriage bolts and some small bearings I had on hand to ensure they spun freely but if I were doing it again, I'd measure and get some shouldered bolts instead. Think they would be able to be kept tighter to the board with a little less vertical play in the plugs.
That said, you still do the majority of the uncoil/straighten as you feed the line through the straightener. If I had less line to hang, straightening it by hand is possible.
About halfway through putting up my lines, I decided to try pushing the line through some small diameter gray PVC conduit I had lying around. With some carefully placed concrete blocks along the conduit to keep it from arching along its length, I got the line just as straight but a lot faster. I used the red shipping/storage caps to keep debris out and pushed it through about a 12' length for the long runs and an 6' section for my drops (6.5').
Final tweaks to fully straighten lines were all done by hand. Then done again as I hung the lines. I was working 12' off the ground and usually ended up slightly bending the lines as I hung everything. No issues, the line is oddly stiff and flexible at the same time.
For corner bends and other small routing direction changes, I just did them by hand. I put the clips up on the wall where I wanted them, clipped the line in and massaged the line to fit the corners the way I wanted.
I only had two spots where I needed small radius bends. One was right off the regulator where I encountered experiential learning on how small a radius you can bend without kinking the line for a 90* bend (~6" radius is as small as I'd go with 1/2" Maxline). The other section just needed two small bends to get around a 2x6 where my garage door opener chain mounts above the garage door. I wouldn't even really call this spot a bend because the clips hold the line about a half inch from the wall anyway and I only made the small bends because my OCD wouldn't let me just let it run across it (which was also just fine).
Overall, I ran about 250' of line including the drops. The hardest part of all of it was my OCD in clip placement and moving and climbing/descending the ladder around a full and still disorganized shop. Bosch's cross line, auto-leveling laser was money in getting everything exactly where I wanted.
I've tested for leaks twice in the last 4 days. Once pressurizing for an hour, once overnight. Not so much as a hiss or a single psi drop during either test.
Hope this helps.