I am posting how I made them, but you can also look up the instructions on many places online.
It is called a sparkleball.
You need 50 cups to make 1 sphere.
Also a string of 50, 60 or 100 lights.
They don't have to be Solo brand cups (I got these at Smart & Final) but be sure to use 9 oz tumblers.
Divide it into 25 cups to make each half.
Divide the 25 cups into a group of 12, a group of 9, and a group of 4.
Arrange the first layer of 12 cups to make a ring.
If you have the correct kind of cups, it will naturally form this shape.
Depending on the style of cups, you can staple them, or melt them together with a hot tool, which is a tool like a wood-burning tool or a soldering iron.
For this project I melted them together with a tool. It smells very bad and I'm sure the fumes are very toxic, so do it in a well ventilated area.
I melted the cups together at one point at the bottom and one point at the lip. About 1/2 inch welds.
These crystal-clear type cups will shatter if you staple them. But you can get a similar shaped cup made of a different kind of plastic.
(I have also tried connected these spheres with clear packing tape, (Not scotch tape) but this doesn't last more than 1 year.)
Next you build up the next row, of 9 cups.
Some people use clothes pins to hold the cups together until they are welded, but I have been doing this awhile. Sometimes you can put a spare cup in the center and it holds up the other cups.
(In this picture I used a can of nuts to hold up the center.)
Finally top it with 4 cups and you get half the sphere.
Repeat this to make the other side.
Also you will make 1 hole in the bottom of the cup to insert the lights.
Using the hot tool. Don't make the hole too big.
(1 hole for a string of 50 lights and 2 holes for a string of 100 lights.)
You want to leave the cord ends hanging out so you can plug it in or hang it.
I kind of press the lights into the hole in a zig-zag pattern.
If you make the hole small enough, the lights will stay put.
I wanted this sphere to last a long time, so I used hot glue around the hole where the lights go in.
Also I used LED lights which are made of plastic.
First you put the lights in one half of the sphere, and then the rest in the other half. It can be tricky.
After using the tool to weld both halves the cups together, I put more hot glue from a glue gun in the seams.
Eventually you end up with the finished product!