FEFCO 0427 Mailer
A one-piece mailer, no glue: rolled-in walls and a tucking lid
At its own sizes
Open it in ParametrIQ CAD
It comes with ParametrIQ CAD: File › Run Parametric… › Packaging › FEFCO 0427 Mailer. Or download its drawing file (.piq) and open it in CAD.