In Treasure of Nadia Gaffer Tape is one of the items that is most often used to craft new items. In the case of Gaffer Tape, it is used for making Rat Traps and the Pickaxe. To make a Rat Trap you need to combine Plastic Wrap, a Roach, a Basic Container, and Gaffer Tape. For the Pickaxe, you need the Wrench Grip, the Grappling Hook, the Pipe Wrench, and the Gaffer Tape.
You will quickly notice that In Treasure of Nadia Gaffer Tape is hard to miss. The first Gaffer Tape is located in the southwestern part of Estero Park on a hill. Since it is located on a hill, it cannot be reached at the beginning of the game. Only when you have the Grappling Hook, you can reach it and pick it up. You get the Grappling Hook by combining Heavy Rope and the Steel Hook. You can find the Heavy Rope at the doctor's workplace. The Steel Hook can be bought at Squallmart. To reach the Gaffer Tape, stand directly at the hill and select the Grappling Hook from the inventory.
The second Gaffer Tape can be found north of the river in the jungle. It is located in the vase. Use the Pickaxe to destroy the vase.
After that, you will find the third Gaffer Tape in the attic above Alia's bedroom.
You will find the fourth Gaffer Tape after destroying the crumbled wall in the church basement.
Finally, you find the fifth Gaffer Tape in the storage room of the doctor's office.