要用acryl, 比硅胶还便宜许多,去建材商店问
https://www.google.de/search?q=acryl&client=tablet-android-samsung&sa=X&biw=1280&bih=800&tbs=vw:l,ss:44&tbm=shop&prmd=isvn&srpd=10914918819062764945&prds=num:1,of:1,epd:4843928245785324789,cid:9425208541466557105&ved=0ahUKEwjg-IjmuaHWAhWEh7QKHaF3CJ8QgjYI6wQ