It's possible to create Custom Objects in Salesforce using the Salesbolt Extension. This process involves the Salesforce Admin first creating a very specific Link that appears on the originating record (the record you are creating the Custom Object from), and the end user clicking the link.
Creating the Link in Salesforce
Please remember that as of now, Salesbolt will only show records in the Extension if they are Lead, Contact, or Account records. So to create this link, do not go to the Object you want to actually create. Instead, go to one of those three objects (Lead, Contact, or Account) that you might want to create the custom object record from.
For example, if you were creating a custom object "Resume/CV" record, that should be a child object of the Contact, then presumably you would go to the Salesforce Object Manager, find the Contact object, and create the Link there.
To create the link, you can have the link visibly appear to be whatever you want (in this example, perhaps "Create Resume/CV Record"). What is very important is that the Link API Name have a very specific format. It must start with "sblink_". So in our example, it might be "sblink_create_resume_cv".
As well as the Name, please structure this as a Detail Page Link that opens in a new window. Please see the screenshot below.
Add Link to Page Layout
Don't forget to add this new link to your page layout! Otherwise your users won't see it.
Distributing this to your Users
Salesbolt is working on an automatic method to distribute page layout updates to all your users. However, this is not finished, so if your users do not see this link immediately, they will need to refresh their cache of Salesforce Configurations.
They would need to follow the instructions in this article to update those settings, https://salesbolt.freshdesk.com/support/solutions/articles/47001188788-refresh-salesforce-settings
Using the Link in the Extension
Once you have created the link, and once each user has updated their settings as per the above article, no further action is needed. Your users should see that link on the summary page of any record that has the link on the page layout.