I use to refill the empty tubes. It wasn't hard just took time. I removed the glue from Elmer's school glue stick, melted it over hot water (I used a small play metal kitchen pot my granddaughter had) until pourable. Used a small funnel to pour the glue into the refill tube. Put on the cap, placed in fridge until set. I knew to make paste from school glue by heating until all the water is removed to the consistency I wanted. But then reason set in, I didn't use the glue pen enough to have so much. The paste could be put in empty school glue sticks to become firm. . Cheaper? I don't know as glue stick are cheap enough.