another trick: even a cheap, opaque projector can enlarge these the size of a wall. as andrew mentioned, big is better sometimes. these projectors can be found in most toy stores for less than 20 bucks. they're also handy to enlarge the work of others, to get a better idea of what certain cuts look like.Thanks for the comments, Normally my drawing skills not bad like this but i havent draw anything in like 4 years so my fingers little bit rustedi am keep practicing on circles. i'll upload another pictures tomorrow and you will see the difference
cheers.