Step 1: Get the parts
I use one from a dvd-rom, the lens was mounted on a square plastic this made easier to handle the piece, be careful, not no damage or scratch the glass
The cd-rom and dvd-rom are similar but they have different focus distance, keep this on mind, you can make two if you can dismantle one of each.
The lens can be mounted on a tube the size of the telescope barrel, searching for parts, i found one that i liked because the size was right, and need little work, the plastic bottle for35 mm film
The other main part is a small metal plate,
You will need 3 little fasteners and 3 little plastic washers.
Step 2: Metal Plate design
This was a solution, based on the fact that is important to center and level the lens on the base, so i think on a 3 point base and later modify this to center the lens more easily it worked on the first trial, since i didn't want to dismantle the piece after the effort to center this on the base I made some drawings to explain the process.
At the end I give the center a square shape to fit the lens base, that already have this shape, but compared with other optical units each have a different shape, you can modify this or just make a round hole related to the shape of the glass.
Use sand paper and a file to finish the part take special care no to cut yourself with the edges.