So one of the players in my group was asking about just how big some of the gear a shadowrunner uses. Things like white noise generators and holo projectors, but also other gear like the area jammers or even an RFID tag eraser. I and the GM gave our idea on the size of this sort of gear but I'd like to find out just what the Dumpshock community thinks.
Has this sort of thing come up in other games or do most GMs just hand wave it away? The size of gear like that can sure make a difference when you need to prep for a wilderness job or sneak something into some place and an object's size makes a difference.

I've mostly considered those things hand-held. It can become a problem when you want it as equipment on a drone (ok, so its special equipment, but how much space does it take up?)

Unless you are going for the kind of gritty 1980's cyberpunk feel, most objects like that are just large enough for them to be used effectively(to have the proper buttons and handles).

Keep a note that what I'm saying below isn't official, just my take on most the objects you mentioned.

A White Noise Generator would be about the size of a cell phone, due to needed a speaker of sufficient size. Higher rating units may well larger, though I'd doubt even industrial strength ones would be alrger than a small boom box.

Holo projectors would be small. It's noted that most commlinks have a small one built in, so one you'd purchase I'd image would be palm sized. Of course stationary units can get much bigger.

A Jammer would be about the size of a commlink, while a high rating one would be a little bigger, Radio Antennas are noted as being a major part of a commlinks size, and a jammer is just a big antenna.

A tag eraser I'd say is about palm sized, it needs to have a strong magnet in it, but unlike most objects it's usually designed to be concealable(though a commercial one would likely be the size of a hand gun.)

A key thing to note is that most gear will get larger at higher ratings, it's simply the nature of the beast.

yeah I've wondered about sizes for these things too. A quick google search seems to bring up hand held jammers and white noise generators.

I've had to worry about this for medkits too. I see them as:

Rating - Size (Usual application)
1 - Altoids box (carried by day hikers)
2 - Heavy Pistol
3 - Laptop Bag (in your car under the front seat)
4 - Sewing Box (Under the sink in the bathroom)
5 - Fishing Tackle Box
6 - Suitcase (carried by Paramedics)

Yeah, I wasn't just looking for sizes on the four things I mentioned but rather a good rule of thumb for those sort of things. TheOOB has a good rule there with most things being hand held.
Medkits was another one brought up by the player at the time. I also looked at the capacity needed to shove some of this gear into armour and medkits and toolkits take up the same amount of capacity, no matter the rating.
Lantzer, I think maybe a suitcase sized medkit is a bit big if you figure the one just down is fishing tackle box size. Depends on the suitcase I suppose.

Some guys have more tackle than others...

More seriously, I was thinking of the bigger tackleboxes, with multiple folding partitioned shelves. Like my in-law has. Admittedly, the size of your hobby box varies with how much hobby-related junk you have. For some folks, "tool-box" means a small tray of tools. For others, it means a wheeled cart that will fit in the back of a pickup.

The suitcase-sized medkit is about right for the top end - there's a limit to how small you can make first aid supplies and keep them useable. Try stabilizing a broken femur with a 2-inch splint. The big models have defibrilators, drugs, and all sorts of specialized supplies jammed into them.

I think I roughly double/triple the size for each rating point on those medkits. I suppose one easy way to look at these mechanically is to give the rating 2 kit a concealability as a Heavy Pistol, and modify the concealability by 2 level for each point of rating up or down. This leads to:

Rating Conceal
1 -2
2 0
3 2
4 4
5 6
6 8

This matches roughly to my earlier rule of thumb.

No it's more a power supply, a cooling system and an antenna. Jammers use and emit a lot more power than a radio uses to communicate. Of course given how "oddly" SR treats jammers who knows.

I second the OOB's suggestions as pretty reasonable, and Mantis is right in that the capacity taken up by medkits in armour is unaffected by rating - this makes some sense to me, as the difference in medkit rating could be more to do with better diagnostics/robohelp than more equipment but YMMV.

I always ask players to write a list of equipment that they are bringing on a run and eyeball it to make sure it seems reasonable ("500m of stealth rope? That seems an awful lot ..."). About the only thing that ever really comes up in gameplay is ammo, and only then if they get caught up in a protracted fight with full auto ...

Capacity on a Handheld Minidrone sensor is [3].

This could fit in a decent amount of sensor options. In one of these, you can contain a Radio Signal Scanner, an Olfactory scanner, and a MAD scanner... all at the same time.

Somewhere I read that a micro (capacity [1]) could fit in a button.

I think things have shrunk a bit from current technology.