How to summarize a text planning grid?

[SURFER349]

So not sure quite what I'm asking here, but seeing if you could give me pointers? Let's say I've got a planning table like this below. I'm trying to think of a way to have a second table that will list each ToolID and a single cell that shows all the 'items' that have X for them, dynamically.

[TABLE="width: 320"]
<colgroup><col width="64" span="5" style="width:48pt"> </colgroup><tbody>[TR]
[TD="class: xl48890, width: 64"]Tool ID[/TD]
[TD="class: xl48891, width: 64"]A[/TD]
[TD="class: xl48890, width: 64"]B[/TD]
[TD="class: xl48890, width: 64"]C[/TD]
[TD="class: xl48890, width: 64"]D[/TD]
[/TR]
[TR]
[TD="class: xl48890"]Group1[/TD]
[TD="class: xl48893"]x[/TD]
[TD="class: xl48893"]x[/TD]
[TD="class: xl48893"]x[/TD]
[TD="class: xl48893"]x[/TD]
[/TR]
[TR]
[TD="class: xl48890"]Group2[/TD]
[TD="class: xl48892"] [/TD]
[TD="class: xl48892"] [/TD]
[TD="class: xl48893"]x[/TD]
[TD="class: xl48893"]x[/TD]
[/TR]
[TR]
[TD="class: xl48890"]Group3[/TD]
[TD="class: xl48892"] [/TD]
[TD="class: xl48892"] [/TD]
[TD="class: xl48893"]x[/TD]
[TD="class: xl48893"]x[/TD]
[/TR]
[TR]
[TD="class: xl48890"]Group4[/TD]
[TD="class: xl48892"] [/TD]
[TD="class: xl48892"] [/TD]
[TD="class: xl48893"]x[/TD]
[TD="class: xl48893"]x[/TD]
[/TR]
[TR]
[TD="class: xl48890"]Group5[/TD]
[TD="class: xl48892"] [/TD]
[TD="class: xl48892"] [/TD]
[TD="class: xl48892"] [/TD]
[TD="class: xl48893"]x[/TD]
[/TR]
[TR]
[TD="class: xl48890"]Group6[/TD]
[TD="class: xl48893"]x[/TD]
[TD="class: xl48893"]x[/TD]
[TD="class: xl48893"]x[/TD]
[TD="class: xl48893"]x[/TD]
[/TR]
</tbody>[/TABLE]

Something like this. The extra kicker is that there are ~100 rows and ~100 columns, so hand writing one big concatenation formula seems daunting.
[TABLE="width: 128"]
<colgroup><col width="64" span="2" style="width:48pt"> </colgroup><tbody>[TR]
[TD="class: xl48892, width: 64"]Tool id[/TD]
[TD="class: xl48892, width: 64"]Items[/TD]
[/TR]
[TR]
[TD="class: xl48891"]Group1[/TD]
[TD="class: xl48891"]A,B,C,D[/TD]
[/TR]
[TR]
[TD="class: xl48891"]Group2[/TD]
[TD="class: xl48891"]C,D[/TD]
[/TR]
[TR]
[TD="class: xl48891"]Group3[/TD]
[TD="class: xl48891"]C,D[/TD]
[/TR]
[TR]
[TD="class: xl48891"]Group4[/TD]
[TD="class: xl48890"]C,D[/TD]
[/TR]
[TR]
[TD="class: xl48891"]Group5[/TD]
[TD="class: xl48890"]D[/TD]
[/TR]
[TR]
[TD="class: xl48891"]Group6[/TD]
[TD="class: xl48890"]A,B,C,D[/TD]
[/TR]
</tbody>[/TABLE]

 

[DRSteele]

This formula requires function TEXTJOIN, which is part of Excel 2016 only. Properly invoke B11 and then copy down.

	A	B	C	D	E
Tool ID	A	B	C	D
Group1	x	x	x	x
Group2	x	x
Group3	x	x
Group4	x	x
Group5	x
Group6	x	x	x	x
Tool id	Items
Group1
Group2
Group3
Group4
Group5
Group6

<colgroup><col style="width: 25pxpx"><col><col><col><col><col></colgroup><thead>
</thead><tbody>
[TD="align: center"]1[/TD]

[TD="align: center"]2[/TD]

[TD="align: center"]3[/TD]

[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]4[/TD]

[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]5[/TD]

[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]6[/TD]

[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]7[/TD]

[TD="align: center"]8[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]9[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]10[/TD]

[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]11[/TD]

[TD="bgcolor: #C6E0B4"]A, B, C, D[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]12[/TD]

[TD="bgcolor: #C6E0B4"]C, D[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]13[/TD]

[TD="bgcolor: #C6E0B4"]C, D[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]14[/TD]

[TD="bgcolor: #C6E0B4"]C, D[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]15[/TD]

[TD="bgcolor: #C6E0B4"]D[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]16[/TD]

[TD="bgcolor: #C6E0B4"]A, B, C, D[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

</tbody>

Sheet13​

[TABLE="width: 85%"]
<tbody>[TR]
[TD]Array Formulas[TABLE="width: 100%"]
<thead>[TR="bgcolor: [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=DAE7F5]#DAE7F5[/URL] "]
[TH="width: 10"]Cell[/TH]
[TH="align: left"]Formula[/TH]
[/TR]
</thead><tbody>[TR]
[TH="width: 10, bgcolor: [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=DAE7F5]#DAE7F5[/URL] "]B11[/TH]
[TD="align: left"]{=TEXTJOIN(", ",1,IF(IF(A11=$A$2:$A$7,$B$2:$E$7,"")="x",$B$1:$E$1,""))}[/TD]
[/TR]
</tbody>[/TABLE]
Entered with Ctrl+Shift+Enter. If entered correctly, Excel will surround with curly braces {}.
Note: Do not try to enter the {} manually yourself[/TD]
[/TR]
</tbody>[/TABLE]