How to Make Sticky Tack
To make sticky tack, remove the glue from an old, partially-dried glue stick. If you don't have an old glue stick, uncap it and leave it out for a few hours to dry. Roll the glue between your palms, stretching and kneading to create the right texture. If you don't have a glue stick, mix 2 parts liquid glue with 1 part liquid starch. Stir in a bowl until the mixture gets to a thick, sticky consistency, then knead it with your hands. Store your sticky tack in an airtight container until you're ready to use it.
Find an old glue stick. You want one that has some glue left that's too dry to spread. If you want, you can use a brand new glue stick. Just let it sit without its cap for a few days so it can dry out and become more tacky. Don't try this with a new glue stick that's still spreadable. The sticky tack will be too sticky, and it could glue your pictures to the wall instead of temporarily adhering them there, like sticky tack does. Roll and stretch the glue. Place it between your palms and roll it around, smoosh it, and form it into a ball, then stretch it out. This will help it dry out a little more and create the right texture for sticky tack. If it's not quite dry, sprinkle a little baby powder onto the glue ball and work it in. The powder will absorb the remaining moisture. Color the sticky tack. Take a marker (preferably blue, the color of real sticky tack) and color the sticky tack. Any type of marker or ink will do. Add a few drops of color, then roll and stretch the glue ball to mix the color in. Wear gloves when coloring the sticky tack to protect your hands from getting stained. Keep adding more color and mixing it in until you're happy with the way it looks. If you're concerned that the sticky tack could leave marks on your pictures, you don't have to add color. Just use the sticky tack as is. It'll work just as well! Enjoy your homemade sticky tack. Take a pinch and stick it to the back of your pictures, posters, and other lightweight items, then press the items against the wall. When you're ready to take them down, the sticky tack will peel right off. Measure out your glue and starch. You'll need 2 tablespoons (29.6 ml) of white glue (also called school glue) and 1 tablespoon (14.8 ml) of liquid starch, the kind that's used to starch shirts. These ingredients will give you a small batch of sticky tack. If you want a larger batch, just remember to use the ratio of 2 parts glue and 1 part starch. Mix the glue and starch. Put them in a container and use a spoon to mix them together. The mixture will immediately begin to stiffen, due to the interaction between the glue and starch. Soon it will form the consistency of sticky tack. Add a few drops of food coloring. Use blue or another fun color to color your sticky tack if you'd like. Add just a few drops, since a little goes a long way. Stir it in so that the ball of sticky tack gets thoroughly colored. Knead it with your hands. Scoop the sticky tack into your hands and knead it so that it becomes firm, but pliable. If you think it feels a little sticky, work in a little more starch. If it's too dry to stick, add a bit more glue. Keep working the sticky tack until it reaches the consistency you want. Use or store the sticky tack. Pinch of a few small pieces to hang a poster or picture. You can store the sticky tack you don't use in an airtight jar or another container. If it gets a little dry before you use it again, you can add more glue and work it in with your hands to achieve the right texture again. 
Find an old glue stick. Roll and stretch the glue. Color the sticky tack. Enjoy your homemade sticky tack. Measure out your glue and starch. Mix the glue and starch. Add a few drops of food coloring. Knead it with your hands. Use or store the sticky tack. 