To use your own font in the Letter Stencil Maker, simply click 'font', then the upload button shown below. This will open up files from your device and allow you to choose one.

Make sure that the file you are choosing is an 'OpenType Font' (OTF) file format.

Please note that your font will not be permanently added to the Letter Stencil Maker, and that you will have to open it again if you wish to use it in the future.