The Sawmill in Zaton is the first place where you can grab a toolkit from but be warrend for twenty or more zombified stalkers in the area. The toolkit is located inside the building on the lower level of the sawmill, to the north. A ladder is inside one of the rooms, and in the attic it leads where you can find ammunition for each assault rifle type, several hand grenades, and medical supplies. the toolkit is on a table at the end of the room.

Comparatively more dangerous, getting the Yanov toolkit requires playing a game of chicken with a mobile Electro anomaly. Even in a SEVA Suit, getting so much as scratched will induce serious bodily harm and quite likely death. By following the tracks away from Yanov station to the south, the player will come across an immobile train. By climbing onto the bridge over it, they can hop down onto the train and run to the end, where an open hatch will drop them down into the train itself. Immediately stepping to the side into the doorways or crouch-jumping onto the train's seats is the only way to avoid the anomaly. Once it reaches the player's end, it will start moving back, and the player needs to follow it. Once they get to the next set of doors, they once again need to move to the side into the doorway to avoid electrocution. Once the electrical anomaly reaches the end and starts moving back towards the player, and then passes by, the player can sprint to the end - stopping to grab the toolkit from the last seat on the left. The player can then escape by jumping out the door on the left.

Slasher and his team are unwittingly guarding the area's local set of fine tools. By paying Slasher's modest cover fee of six pieces of bread, sausage or rations, the player can enter their camp and roam about freely as long as their guns are holstered. If you take your shooter out even near the entry of the camp, Slasher and his men become hostile. The fine toolkit is right beside the three Mercs in the south-western area, sitting atop a crate beside one of them.

Yet another important item inside the Jupiter Factory area. Located in a separated area from the rest of the complex, it can be accessed by taking the road to the west of the Concrete Bath anomaly with some care, as bandits will likely ambush the player from further to the west if they haven't already been cleared out. Once past the gate, the toolkits are found inside the big orange building on the player's left, specifically on the top floor. This must be done with some care as that floor is host to an electrical anomaly field, and the low pipes will prevent the player from simply using bolts and running to get through safely. The toolkit is located inside the dark green locker at the very end of the floor, and the door to the left of it can be opened to provide an easy one-way escape route.

The first set is located inside the Pripyat Department Store, located in the basement behind the stairs. The player does not need to go down into the extremely dangerous anomaly field - but they do need to deal with a great number of Rodents inside the department store itself, as well as the labyrinth of doors required to find the basement entrance.

The lower section of the basement is an artifact spawning area, but is an extremely dangerous anomaly field. consisting of mobile burners and chemical anomalies. A SEVA Suit is a must for remotely safe navigation.

The kit itself is located on the level above the anomaly/artifact area, on a table near a yellow light, to the front-right of the stairs as you enter from ground-level.

The second set is located inside the other Old Service Center, which is marked on the player's Pripyat map. It's specifically located in the second floor, and is fairly more difficult to acquire. it requires navigating a pair of electroshock anomaly fields, fighting with a Burer in a compact space, and likely dealing with several Exoskeleton zombies. Once the player reaches the top floor and grabs the calibration kit, they can unlock a door which leads into a stairwell, taking them right down to the bottom floor and out into safety.

I got all the info from the STALKER WIKIA.
I just wanted to upload this to the Steam community because there where no guides for it and this is much easyer then searching it all on the web if you are in-game.

I hope you guys like it!