When you start painting plastic blanks, you may want to put some superglue around the hook hanger eyes and line tie eye. Some of the blanks may leak around those spots. Sometimes your paint and clear coat doesn't get in around the eyes to seal those spots. You can buy 30 cheap small arts & crafts paint brushes for $2 at walmart to smear the superglue around those spots.
There are several suppliers who make those types of blanks. You can check the pinned post at the top of the hard bait forum. Here are some links
https://www.sheltfishingtackle.com/shelts-rap-ko-shad-blanks-p-100.html
https://lurebuild.com/ols/products/3-flicker-minnow
https://fishheadcustomlures.com/d7-crankbait-chrome/
https://fishheadcustomlures.com/d7-crankbait/
https://backwateroutfitting.com/product/rap-crank-unpainted/
https://www.sugartitcustomlures.com/product-page/basic-5-shad
I find the narrow rolls of painting tape to be useful when painting small blanks. 3M makes 1/8" (0.125") and 1/4" (0.25") rolls.
https://www.amazon.com/3M-2090-0-125in-60yd-Masking/dp/B007Y7GPQU/ref=sr_1_10?crid=3Q6MY49OQXCYU&keywords=3M+2080+ScotchBlue+Painters+Tape+–+0.125+in.&qid=1702823144&s=industrial&sprefix=3m+2080+scotchblue+painters+tape+0.125+in.%2Cindustrial%2C112&sr=1-10
https://www.amazon.com/2090-ScotchBlue-Painters-Tape-Preparation/dp/B0079NPE6G/ref=sr_1_4?crid=NOB3GQWOLAX0&keywords=3M+2090+ScotchBlue+Painters+Tape+-+0.25+in&qid=1702823395&s=industrial&sprefix=3m+2090+scotchblue+painters+tape+-+0.25+in%2Cindustrial%2C104&sr=1-4