Let me just start off by saying that the double rainbow is an amazing design. You don't need any obscure materials like 1.5" thinwall PVC, you can have as much draw as you want, and it wont murder your face! The double rainbow can be built in any design you want. The only requirement is that the plunger tube and spring/catch are separate.
This double rainbow is also very special because it is the first rainbow catch that I cut entirely with my scroll saw. I didn't use a hole saw to cut out any parts. Surprisingly, the circles turned out almost perfectly and the catch lines up in PVC better than the hole-saw-cut ones.
The design that I went with on this is based off of Modman712's (based off of NoM's). This design uses two sections of clear PVC and two sections of opaque. I did change the design a bit though. I went with a PVC tee for the stock and cut the top opaque PVC diagonally then put polycarb over it. I will be changing the stock into an elbow with and endcap because it will give the blaster a better look.
I was a little bit hesitant to build one of these at first because they don't look very stable. I can assure you that this is one of the most stable blasters that I have ever built. Everything is also mechanically fastened, making it easy to take apart for maintenance. This thing is also extremely comfy. I think it is because I'm not worried about my face getting cut up from the plunger rod and that priming is very smooth. Not only is it super comfy, but it is shorter than a +bow or pumpsnap/rainbowpump when you put a hopper in it.
I took a picture of the spring with the 1" PVC off of the blaster to show that the spring gets full compression. Because of the K26 getting full compression, this blaster gets amazing ranges. It is getting the same (if not higher) ranges of my +bow. I think it might be getting better ranges than my +bow because it has a nearly perfect seal and full compression.
You can see that the double rainbow is getting a little bit more draw than my +bow which might also explain the amazing performance. I only have a few more things to do with my double rainbow to make it completely finished. I am going to paint the opaque PVC, get a shorter bolt for priming, and stain the handle. After that, it will compete for being my primary against my +bow. I can't emphasize enough how awesome double rainbows are and if you are between building one of these or a rainbow pump, build the double rainbow.
This is my last project of the summer, but that doesn't mean I will stop making new things. I definitely won't be able to post as frequently even though I will still be working on stuff. I have a blaster planned for the NerfHaven homemade write up contest but other than that, I have nothing else. What do you think I should build next?