Affinity Designer 1.7 seems to have no way of creating a vector shape and saving it as a preset. One guy on youtube said you could but failed to explain how. In photoshop after creating a shape I just create it, right click define custom shape, then name it and it's added to my custom shape presets. This seems like it should be a no brainer in designer but when I hit the presets cog and get the create preset pop up it's always grayed out even if the shape I have created is selected. Here are the instructions on Designer help:
To create new Custom tool presets:
Select the shape you wish to create a new preset for and edit it to your liking.
From the shape's context toolbar, click the Presets icon.
From the pop up panel, select Create Preset from the preferences menu. Enter a name and category for your new preset, then click Create.
It does not work, very frustrating.