Would you trust a German carpenter to surgically install a temporary vasectomy switch into your vas deferens? Before you answer, consider that this German carpenter has already implanted two test prototypes into his own genitals and has nothing but positives to report.

“Many doctors that I have consulted, have not taken me seriously,” Clemens Bimek told the German magazine Spiegel. “But there were also some who have encouraged me to continue to tinker and who have supported me with knowledge.”

Bimek is the only test subject for the self-named device, having made his first installation in 2009 and testing and improving his patented sperm switch over the last six years. The Bimek SLV works thusly: the tiny valve — about the size of a gummy bear — is attached to the vas deferens with a switch accessible just underneath the scrotum’s skin. When activated, the valve closes and diverts the sperm cells that would normally travel through the vas deferns to the semen, resulting in temporary sterility. Assuming the switch’s medical-grade polymer stays in good condition (a switch closed for up to three months might suffer clogging) it could work as effective birth control for the lifetime of its host.

According the Bimek’s marketing to investors, the company hopes to target “millions of men around the world” who would prefer this to a vasectomy. Bimek explains the device’s convenience:

“The valve is implanted during an outpatient surgery that lasts about 30 minutes. Opening and closing the Bimek SLV requires a simple flip of a switch that can be done from outside the skin of the scrotum.”

A male contraceptive pill is probably at best years away but California’s Parsemus Foundation is already researching a temporary vasectomy using a polymer called Vasalgel, which is injected into the scrotal tube to block sperm. Presumably, you’d have to go to a doctor to get your works unblocked rather than simply flipping a switch.

No, it’s not for sale yet. Bimek hopes to have a final device on the market by 2018, but first wants at least 25 men for testing.