Hi,
Surely, There must be info, plans, directions, etc.... on making optical devices around. Projects like this would be far more than just making a simple scope. The real fun is in the learning of new skills and being able to say "I built it."
Paul
If your trying to save money,then the answer is no,you really cant. If you think it would be a cool project,then by all means do it. To start,your going to have to learn how optics work. Try a physics book from the library. Im going to assume you need a very basic one,becuase if you didnt,you would have something of an idea of what was involved. Your going to have to understand how systems of lenses work. I would suggest playing around with the lenses from the scopes you have to understand how it works,but not actually building anything permentant out of them. In other words,play around with cardboard tubes and masking tape. You will have to figure out the focal lengths of the lenses you have for instance to do anything with them. This is the sort of thing we did back in basic physics classes. (the professor would give us a box of lenses and we would proceed to figure out things like the focal lengths of the lenses,the refractive index of the glass etc.)
Once you understand how it works and can take some random lenses you DONT know anything about,figure out what they are,then figure out the distances you need to make a working scope in a cardboard tube,you can make a real scope in a nice metal housing. Your dealing with cylindrical parts so to do a decent job you will need a lathe. If your putting that much work into it,you probobally want to get some decent lenses from a vendor that has a good selection. There are several of them out there. (and they can range from cheap to expensive just like scopes,for the same reasons) One of the big issues is coatings. The higher end optics have prorietary coatings that the vendors have developed just for their scopes and other optics. Im guessing similar coatings ,or in some cases even the same coatings will be available,but probobally on a custom basis for ludicrious amounts of money. In other words,a physicist doing an experiment that requires that,is willing to pay a thousand dollars for a lense (or even 10,000) ,but you have to stick with the stuff out of the catalog,and its still going to be on the pricey side.
There are sources of surplus optics,some of it quite good quality. The problem is,you have to take what they have,which means designing around what is available.
Finally,while I have not looked at whats inside rifle scopes,I have conisdered the idea of makign a custom camera lense. What I found when I looked at that idea,was that a cheap camera lense has few lenses inside the housing. A expensive one has many. The magnification may be the same but those lenses are used to reduce various forms of distortion. Those,and the coatings are what differentiate a cheap lense from an expensive one. The same I suspect goes for scopes.
If you want somethign similar to a old fasioned scope,one place to look for ideas might be old patents. The problem of course is,such things will be highly technical and not much use without a good understanding of how optics work. They probobally wont give you dimensions and will use a very technical,and for older ones,archaic language.
If your the sort of person that watches the discover channel all the time,and likes to play around with magnets (or lenses) then you might like to do it. If you dont really think learning a field of physics (optics) is fun,then your not going to get through it. Start by googling things like "optics" "lenses","ray optics","virtual image","real image","refractive index" and read through the stuff you find. If it all seems like that boring physics class that you had to sit through in high school then you should just buy a nice scope. For that matter,just buy a nice scope anyway,because if you want to do somehting like that,its a long term project,and you will need something to shoot in the mean time. Im not saying dont do it,becuase it could be an interesting project for someone who likes those sorts of things. Its just not for everyone. (The people who it IS for often become engineers or physicists actually,where they do that sort of thing for a living)