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.