You can only do so much with under-mattress tie downs and bed frame restraints. Crosses and benches are obvious and often aren't easy to quickly disassemble and stuff in a closet when you forgot your mother-in-law is coming over or you don't want to make the plumber uncomfortable while they fix a leak. Of course one of the obvious perks of having a massage chair is that you may even get your partner to give you a massage after you play just by having one around.
For those who want something that might fold up for easy storage or may be left out without anyone raising an eyebrow consider a massage chair. As a petite woman I appreciate using a chair in my dungeon because it brings my taller subjects down to a manageable height for me to do as I wish. Made from sturdy lightweight materials, it can be easily moved to any room in my home, or folded down and stored in a coat closet or under a bed. The chair allows submissives with limited mobility and flexibility in their limbs to be comfortably bound without causing unnecessary strain or injury to them. Most models are adjustable so you can change the height and angle for your play partner allowing for a range of positions and play. You can even have your play partner sit backwards on the chair to face you for an entertaining balancing act while you play.
A massage chair was one of my first furnishings in my dungeon, becoming one of my most loved and used implements. Even now I am still coming up with new ways to use it in scene. Be warned, once you start looking at a massage chair with kink in mind, you might turn an eye to other household items. Pervertables can be great fun, but remember to do your homework on safety precautions and kink techniques before you search your house for an undiscovered favorite toy. Knowing how to play with imagination and safety in mind can make you a sexy play partner.