Make yourself a nice cellphone stand from cap of bottle in 5 minutes!
Despite small diameter such construction is very stable (see video)
Step 1: Get a Cap From a Bottle
Just take some bigger plastic cap from bottle (5 litre bottles - ~ 3-4 cm in diameter). You probably throw out such caps every day :)
Step 2: Cut Out Gaps
Cut gaps in cap like in picture. Cut with sharp knife. Adjust angle and width of gaps to size of your cellphone.. Cut more if phone doesn't fit. Keep in mind that gaps should be away from center on some side)