Most people searching this phrase at 11pm should not buy a button box at all. They should build one. An afternoon, roughly $50 to $80 in parts from Amazon, and you end up with something better laid out than anything you can buy, because you’re the one who decided where the brake bias encoder goes. If soldering genuinely isn’t happening in your life, the best off-the-shelf answer for a desk or rig setup is a Derek Speare Designs box (DSD, around $180 to $350 depending on layout), and the best cheap answer is one of the generic aluminium sim racing button boxes floating around Amazon for $70 to $130. They’re all made in the same few factories with the same switches. Buy on layout and price, not on the seller’s name.

Here’s the part the listicles skip: you will use about eight inputs. I have a 32-input box bolted to my rig. Eleven of those get mapped. Two of the eleven are “oh no” buttons I hit by accident reaching for something else. Every extra switch past that count is decoration that costs money and eats desk space. So before you spend $300 on a 24-button wireless unit, open your sim, look at what you actually bind mid-stint, and count.

What you’re actually buying

A button box is a USB device that reports button presses. That’s the whole product. There is no firmware magic, no latency story worth telling, no “sim racing grade” anything. The differences that matter are switch feel, whether it has real rotary encoders, how it mounts, and whether the USB connector survives being yanked.

Where the money goes on premium units is machining and wheel-side mounting. Ascher Racing and Cube Controls build boxes that clamp to a wheel rim or sit inside a formula-style hub, wireless, with a 2.4GHz dongle. The Ascher B16M-USB is around €290, and the wireless B24M pushes toward €400. Those are genuinely nice objects. They’re also solving a problem most people don’t have. If your box is going to sit on a desk or bolt to an 80/20 rail at your left hand, none of that machining does anything for your lap time.

Fanatec’s ClubSport Button Module Endurance (around $180) is the odd one out because it sits above the wheel hub and gives you two encoders plus a set of buttons where your thumbs already are. It’s good hardware. It’s also Fanatec, which since the Corsair acquisition still means you should expect shipping to take a while and RMA threads to read like breakup letters. If you’re already deep in Fanatec gear it makes sense. If you’re not, it’s a strange first purchase.

The DIY route, properly

Three brains are worth knowing about, and the choice between them decides everything else.

The cheapest is a zero-delay USB arcade encoder board, about $8. It’s the thing arcade cabinet builders use. Plug in, Windows sees a gamepad, no code, no drivers. You get 12 buttons on the header plus 5 more on the joystick harness pins if you wire them as buttons, so call it 17. The catch is real and you should know it before you order: these boards cannot read rotary encoders. They also report two analog axes that sit dead centre forever, which some sims will happily offer you as a steering input. Ignore it.

Second option, the Leo Bodnar BBI-32, around £33 plus shipping from the UK. Thirty-two inputs, proper rotary encoder support with debounce handled in firmware, screw terminals instead of headers so you can wire it with a screwdriver and zero solder. This is the one I’d point most people at. Bodnar’s boards have been in sim rigs for over a decade and they just work. His BU0836X (~£40) adds analog axes if you ever want to hang a load cell or a handbrake off the same board.

Third, an Arduino Pro Micro clone for about $6, flashed with MMJoy2. MMJoy2 is a Windows GUI, not code, so “flashing” means clicking through a config screen. You get up to 128 buttons via a switch matrix, encoder support in three different modes, and total control. It’s the most capable and the most likely to eat an evening. The USB-C versions are worth the extra two dollars because the micro-USB port on the cheap ones tears off the PCB eventually, usually while you’re reaching for something in the dark.

Switches, and the toggle trap

Get EC11 rotary encoders, and pay attention to one number: detents versus pulses. You want 20 detents per rotation with 20 pulses per rotation. A lot of cheap listings sell 30-detent/15-pulse encoders, which means every other click does absolutely nothing. Adjusting brake bias in a Porsche 963 down the Mulsanne and having half your clicks vanish is a specific kind of irritating. Buy the 20/20.

Now the toggle switch problem, which nobody mentions until you’ve already bought six of them. A latching toggle stays closed when you flip it up. The sim sees a button held down forever. For an iRacing command like the pit limiter, which fires on press, that means flipping up sends one press and flipping down sends another, and your limiter state and switch position drift apart within a lap. What you want is MTS-103 momentary toggles (ON-OFF-(ON), spring return on one side or both). They snap back, they send a clean press, and they feel fantastic. Latching toggles are only correct for things that genuinely want a held input, or if you’re routing everything through SimHub anyway.

For the main buttons, 16mm or 19mm panel-mount momentary switches with a metal body. The 12mm plastic ones feel cheap through a glove. Arcade-style buttons are fine and cost nothing, but the microswitches go mushy after a season of heavy use, and they’re loud enough that people will hear them on Discord.

Enclosure and wiring

A Hammond 1590-series diecast aluminium box is the standard answer, around $15 to $25, and it drills cleanly with a step bit. If you’d rather not drill, plenty of Amazon sellers list pre-drilled aluminium button box shells with no electronics for $25 to $40, which is a good middle path: their panel cutouts, your switches, your brain board.

Wire it as a common-ground bus. One wire daisy-chained across every switch’s ground leg, then individual signal wires back to the board. Twenty minutes of soldering, and the mess inside will look worse than it is. Use 22AWG silicone-jacketed wire because PVC wire goes stiff and cracks near solder joints. Add strain relief at the USB port, a zip tie anchored to the case is enough. That single zip tie is the difference between a box that lasts five years and one that dies when someone trips over the cable.

Label it with a Brother P-touch or engraved acrylic overlays if you’re feeling fancy. You will not remember which unlabelled toggle is the wiper after two weeks off.

Mounting, and why your box will annoy you

Left of the wheel, angled toward you, roughly at the height of your thigh. That’s the position that works. Mounted flat on the desk means you look down and take your eyes off the apex, which is a real cost in a wheel-to-wheel restart at the Glen.

3M Dual Lock beats velcro for desk mounting by a wide margin, and it survives being pulled off and reattached. For rig mounting, M5 T-nuts into 80/20 extrusion, or a Monstertech or Sim Lab bracket if you want it adjustable. The thing that catches people out is that a button box on a flexy desk arm becomes a lever, and every jab at the pit limiter wobbles your wheel base. If you’re already fighting desk flex with a direct drive, don’t hang more mass off the same surface.

Sim by sim, briefly

iRacing handles high button counts without complaint and its encoder mapping is clean: bind increment and decrement separately for brake bias, and put ABS and traction control on a second encoder. Assetto Corsa Competizione is the one that benefits most from encoders, because you’re adjusting TC and ABS constantly through a stint at Spa in the 296, and clicking a knob beats digging through the MFD. Le Mans Ultimate and rF2 both read generic HID fine. Gran Turismo 7 does not. PS5 and Xbox do not accept generic USB HID button boxes at all, full stop, so if you’re on console your only route is a console-licensed wheel or hub with the buttons built in.

One Windows quirk that generates a support thread a week: the Game Controllers test panel only displays 32 buttons. If you built a 48-input box, buttons 33 and up look like they’re missing. They’re not. They map fine in-sim. The test panel is just old.

FAQ

My wheel already has buttons. Do I need this? If your wheel has two encoders and eight buttons, probably not. The case for a box is stalks, toggles, and things you set once per stint rather than mid-corner. Endurance racers with pit stop routines and lighting toggles get real use out of one. Sprint racers in GT3 mostly don’t.

Wireless or wired? Wired, unless the box is mounting on the wheel itself and you’d otherwise be running a cable through a quick release. Wireless boxes add batteries to charge, a dongle to lose, and a pairing step that occasionally decides not to happen five minutes before a league race.

How many buttons should I get? Count what you bind now and add four. For most people that lands at 12 to 16 inputs plus two encoders, which a $45 Bodnar board covers with room left over.

Before you order

Check the encoder spec on the listing. If it says 30 detents and 15 pulses, or doesn’t say at all, skip it. Check that the box has real screw or bolt mounting points on the back rather than just adhesive pads. And measure the space to the left of your wheel before you buy a wide unit, because a 250mm box does not fit between a rim and a desk edge no matter how much you want it to.

Buy the DSD if you want something built well by people who answer email and you’re done thinking about it. Buy a generic Amazon aluminium box if you want inputs tonight for under $100 and don’t mind mediocre switch feel. Build one around a Bodnar BBI-32 with MTS-103 toggles and 20/20 EC11 encoders if you want the best version of this for the least money, which is what I’d tell a friend.