Стекой формуют заготовку.

Стекой means with a steka. A стека is a small modeling/sculpting tool, especially used with clay, wax, or similar materials. In English, depending on context, it might be called a modeling tool, sculpting tool, or sometimes a spatula-like tool.

So this word names the instrument used to shape the object.

Because стекой is the instrumental singular form of стека.

Russian often uses the instrumental case to show the means or tool used to do something.

Here the implied question is:

• чем? = with what?

Answer:

• стекой = with a modeling tool

So:

• стека = dictionary form, nominative
• стеку = accusative singular
• стекой = instrumental singular

In this sentence, the instrumental is required because the word expresses the tool used for the action.

Because Russian very often expresses instrument with the instrumental case alone, without a preposition.

So Russian says:

• Стекой формуют заготовку.

Literally, that is something like:

• They shape the workpiece with a modeling tool.

You could sometimes use a longer phrase like с помощью стеки (with the help of a modeling tool), but that is less direct and less natural here. The simple instrumental стекой is the normal choice.

This is a very common Russian pattern. The verb is in 3rd person plural, but the subject is not stated because it is either unknown, unimportant, or obvious from context.

So формуют literally means they shape/mold, but Russian often uses this structure where English might prefer:

• they shape the blank
• the blank is shaped
• one shapes the blank

In technical descriptions, instructions, and process descriptions, this is especially common. It keeps the focus on the action, not on who is doing it.

Yes. Формуют is present tense, from the imperfective verb формовать.

But in Russian, the present tense is often used in:

• technical descriptions
• recipes
• manuals
• step-by-step process explanations
• general statements about how something is done

So here it does not necessarily mean right now, at this second. It can mean:

• this is how they shape it
• this is how the blank is shaped
• the blank is shaped with a modeling tool

This is similar to English uses like:

• First, they heat the metal. Then they shape the piece.

Заготовку is accusative singular of заготовка.

It is in the accusative because it is the direct object of the verb формуют.

The action is being done to the blank/workpiece/preform, so Russian marks it as the object:

• формуют что?
• заготовку

So the structure is:

• стекой = with what? → instrumental
• формуют = shape/mold
• заготовку = what? → accusative direct object

Russian word order is more flexible than English word order. The basic meaning stays the same, but the emphasis changes.

Стекой формуют заготовку puts стекой first, so it highlights the tool. This often happens when:

• the tool is important
• the tool contrasts with another tool
• the previous sentence was already about tools or methods

Other possible orders:

• Заготовку формуют стекой.
  More neutral if the main topic is the workpiece.

• Формуют заготовку стекой.
  Also possible, especially in a process description.

So the sentence you were given probably starts with Стекой because the instrument is the information being emphasized.

It is an unspecified they.

Depending on context, it could mean:

• workers
• craftsmen
• potters
• technicians
• operators
• people in general who perform this step

Russian often leaves that vague on purpose. The sentence is about how the object is shaped, not about exactly who does it.

So even though the verb is active in form, English may translate it more naturally as a passive:

• The blank is shaped with a modeling tool.

This is a very useful question, because the verbs are related in meaning but not interchangeable.

формовать usually means:

• to mold
• to shape into a form
• to give shape to a material or piece, especially in technical/manufacturing contexts

Typical objects are things like:

• clay
• metal
• dough
• a workpiece
• a blank

формировать is broader and often means:

• to form
• to create
• to build up
• to organize
• to shape in an abstract or general sense

For example, формировать характер = to form someone's character.

So in this sentence, формуют заготовку is correct because this is a physical shaping process. Формируют заготовку would usually sound less precise or less natural in this technical meaning.

Формовать is imperfective.

Here that makes sense because the sentence describes:

• a process
• a repeated method
• a general procedure
• an ongoing action in a technical description

A perfective form such as сформовать would focus more on completion:

• сформуют заготовку = they will shape/mold the blank completely

So:

• формуют = process / general method / repeated action
• сформуют = completed result, often future in form

In manuals and descriptions of how something is done, the imperfective is often the natural choice.