These realistic webs are made out of silicone glue, and can be removed without leaving stains.
This instructable is a bit late for the faux-real contest, and a bit late for april fools, but it still is a funny prank for someone who is scared of spiders! (Arachnophobia is the most common phobia there is!)
Step 1: How to Identify Silicone Glue:
It is clear, not many bubbles, sticks to anything, is waterproof and does not dissolve styrofoam.
(You could also just read the label)!
Step 2: Find a Corner to Start Your Web On.
Choose a corner that has a fair amount of bumps, because they help the glue stick properly.
Step 3: Starting the Web
Squirt out some glue onto the nozzle of the bottle and touch it to the surface you want to stick it on.
Then pull the bottle away like shown.
It will create a long string, like a spider's, and to stick the string down you squirt out more glue and stick it on.
Step 4: Main Support
For the main support strings, put the first string at the highest point of the to-be web,
and the second will go a bit below. If the web is big, you can add more support.
Step 5: Vertical Strings
For vertical strings you have to start the string at the bottom of the web and end it at the top support string.
Sticking a string to a string is a bit tricky, so you will have to try multiple times.
Step 6: Needs Something?
When the web is half done, its time for bugs!
Get some black plastic pieces and stick the on the web. When they are stuck you can continue your web over them.
Step 7: Slimy!
A creepy, slimy spiderweb!
Have fun with it!