Learn Russian: Внутри мастерской гончар создаёт уникальную керамику. - Inside the workshop, the potter creates unique ceramics.

The word мастерская is an adjectival noun. It functions as a noun but declines exactly like a feminine adjective. Since the preposition внутри (inside) requires the genitive case, the feminine singular adjective ending changes to -ой, giving us мастерской.

What is the difference between using внутри мастерской and just в мастерской?

В мастерской is the standard way to say "in the workshop." Using внутри specifically emphasizes the interior physical space ("inside the workshop"), which paints a clearer, more atmospheric picture of the setting.

The infinitive for "creates" is создавать. Why does the -ва- disappear in создаёт?

Verbs ending in -давать (as well as -знавать and -ставать) drop the -ва- suffix in the present tense. Therefore, создавать conjugates as создаю, создаёшь, and in the third-person singular form used here, создаёт.

Why is керамику in the singular form when the English translation uses the plural "ceramics"?

In Russian, керамика is treated as a singular, uncountable mass noun when referring to pottery or the craft as a whole (much like the word "pottery" in English). It takes the accusative singular form керамику here because it is the direct object of the verb.