Learn Turkish: Mezurayı ve spatulayı saklama kutusunda tutmakta fayda var. - There is benefit in keeping the measuring tape and the spatula in the storage box.

This is a verbal noun purpose compound, matching the current lesson. We take the short verbal noun saklama (storing) and combine it with kutu (box). To link them, we add the possessive suffix -su to the second word, making saklama kutusu (storage box). Finally, to say 'in the storage box', we add the buffer -n- and the locative case -da, giving us saklama kutusunda.

Why do we use the locative case on the infinitive in tutmakta?

Adding the locative case -da/-de/-ta/-te to a full infinitive (-mak/-mek) roughly translates to 'in doing [action]'. It is extremely common to pair this structure with fayda var (there is benefit) or yarar var to mean 'there is a benefit in doing...' or 'it is a good idea to do...'. Thus, tutmakta fayda var means 'there is a benefit in keeping'.

Do infinitives like tutmak always require case markers on their objects, like we see with mezurayı?

Yes! Even though tutmak (to keep/hold) acts as a noun here in its infinitive form, it still governs its objects just like a regular verb. Since you are talking about keeping the specific measuring tape and spatula, they both take the definite accusative suffix -yı.

What is the difference between the verbs saklamak and tutmak in this context?