A pen for cosmetic, writing, drawing, sketching and/or marking purposes includes an inner part and an outer part, wherein at least a portion of the inner part is accommodated in the outer part and is fastened therein. A fastening device between the inner part and the outer part serves to fasten the inner part to the outer part, wherein the fastening device is elastically deformable and is deformed in the installed state against its elastic restoring force. The fastening device is supported between the inner part and the outer part by the elastic restoring force to fasten the inner part to the outer part.