Use the custom block 'Create Healthbar' to create the healthbar, you can also drop it in other sprites to use their position! Make sure to broadcast 'Update - Healthbar' at the start of your game loop! I did this so if you are doing a pen game it won't get disturbed by the erase all block... Easily backpackable, go ahead and use it!
I don't really need credit since other people have done it as well, if you want you can credit. :) Based on @griffpatch 's Health Bar, but this time with the pen extension instead of wasting clones lol.