kabin ni etuke wo suru.

It is read:

かびん に えつけ を する

Word by word:

• 花瓶（かびん） = vase
• に = on / onto / to
• 絵付け（えつけ） = decorative painting; applying a painted design
• をする = to do

Also, in normal Japanese writing, this would usually be written without spaces:

花瓶に絵付けをする。

Here, に marks the target or surface that receives the action.

So 花瓶に絵付けをする means something like:

• do decorative painting on a vase
• apply a design to a vase

The vase is not the direct object of する. Instead, it is the thing the decoration is being applied to.

Because Japanese is structuring the action as:

• 絵付け = the activity being done
• 花瓶に = the place/target the activity is directed to

So the grammar is:

• 花瓶に = on the vase
• 絵付けをする = do decorative painting

In English, we might naturally say decorate the vase or paint a design on the vase, where vase feels like the direct object. Japanese often packages this differently.

So:

• 花瓶に絵付けをする = do decorative painting on the vase

not:

• 花瓶を絵付けをする ❌

絵付け means painting a design onto an object, especially as decoration.

It is often used for things like:

• pottery
• ceramics
• cups
• plates
• vases
• traditional crafts

So it is more specific than just drawing a picture.

For example:

• 絵を描く = draw a picture
• 絵付けをする = paint a decorative design onto an object

That is why 絵付け fits well with 花瓶.

Yes. 絵付け is a suru-noun, so both of these are possible:

• 花瓶に絵付けをする
• 花瓶に絵付けする

The version with をする can sound a little more explicit or textbook-like. The shorter 絵付けする is also common.

This is similar to pairs like:

• 勉強をする
• 勉強する

Both mean basically the same thing.

Yes, but that is completely normal in Japanese.

Japanese often leaves out the subject when it is clear from context.

So depending on the situation, this could mean:

• I decorate a vase
• She decorates a vase
• We will paint a design on the vase
• (Someone) decorates the vase

If you want to state the subject, you can add it:

• 私は花瓶に絵付けをする。 = I decorate a vase / I will paint a design on a vase.

する is the plain, non-past form.

In Japanese, the non-past can mean:

• a present/habitual action: (I) decorate vases
• a future action: (I) will decorate a vase

So the exact time depends on context.

Polite version:

• 花瓶に絵付けをします。

Past version:

• 花瓶に絵付けをした。 = decorated a vase / did decorative painting on a vase

Yes, it is natural, especially in a craft or pottery context.

It sounds like:

• decorating a vase in a workshop
• painting a design onto ceramic ware
• explaining a craft activity

A useful contrast:

• 花瓶に絵付けをする = paint a decorative design onto a vase
• 花瓶の絵を描く = draw a picture of a vase

So に and の create very different meanings:

• 花瓶に = on the vase
• 花瓶の絵 = a picture of a vase

They are probably there just to help learners see the parts more clearly.

Normally, Japanese is written without spaces:

• 花瓶に絵付けをする。

Learning materials often add spaces to show:

• where one word ends
• where particles are
• how the sentence is built

So the spaced version is for readability, not standard writing.