Here is a tutorial to help you achieving this metallic effect I used in my last Copier-Créer drawings:
It is easy. Let's start.
First, create a new document quite large — here 5400px x 8000px.
Fill the first layer with a dark or colored background — here I used pure
Draw a white shape using the pencil tool on a new layer — here a friendly Jack Nicholson (download the drawing).
Create a black to white vertical gradient on a new layer.
alt + click on the Layer 3 (gradient) to create a clipping mask with the Layer 2 (drawing).
cmd + click on the Layer 2 (drawing) to load selection.
shift + cmd + C to copy merged, then cmd + N to create a new document, validate, then cmd + V to paste.
Go to Image > Mode > Grayscale then validate.
Go to Image > Mode > Bitmap…. Validate the modal by clicking OK. Then pick the following options and validate:
Tip: You can customize the Output option for a different effect, more or less soft.
Now you have a sweet bitmap.
cmd + A to select all, then cmd + C to copy and cmd + W to close the document. Then cmd + V to paste in your main document. The Layer 4 (bitmap) must be clipped in the Layer 2 (drawing).
Hide the Layer 3 (gradient). Then transform the Layer 4 (bitmap) to fit the artboard and validate.
Tip: No need to make this clean. It is better to have a little gap.
Now cmd + alt + shift + S to save for web, pick the following options (GIF, Restrictive, No Dither) then validate:
Open in Photoshop the GIF file you just created.
cmd + A to select all, then cmd + C to copy and cmd + W to close the document. Then create a new layer in your main document and cmd + V to paste.
cmd + S to save your document. Et voilà !
Have a nice weekend everyone!