Very nice looking Blaster =) You even did that little "thing" on the ejection port, that's one of the things I will most likely opt out on in this build.
The link I will definately save for later though.
The way I see it, this build will be a "learning by doing" project, and then later down the road I might pick up a second more serious build, adding to knowledge from the first Blaster. I'm currently doing this in a one room apartment so work space is a bit problematic, which is why I don't want to drag this project too far.
Then again, so far I've decided to try and hollow out the scope for some sort of lens replica, add some better looking screws, doing a removable magazine and securing the folding stock with drill holes, so I've landed in something in between at the moment. Doing a spring is probably not that difficult, but if I do, I will definately just glue/screw it in position. That's when I came up with this alternative idea instead.
The idea would be to just fill the whole chamber with a plastic pipe, then secure the pin to a separate strip of plastic, at the moment it barely moves inside the pipe, but some sanding I think would solve that. It's crude, but a bit easier than doing the spring, and a nice touch to be able to move it. But I dunno... might just be a crazy idea and someone should talk me out of it =P
Added some pictures to clarify.
The tube would naturally be longer. I just used the part I did if I go with a spring build.