Then let me assume that you used the GAM curve in waver, with
peak 1. Let me further assume that the beta coefficient that
you want to use resides in sub-brick 3 of func_slim+orig.

Try:

waver -GAM -tstim 0 -dt 1 -peak 1 > wav.1D
3dcalc -a wav.1D -b func_slim+orig\[3] -expr 'a*b' -prefix resp_3

The waver command creates a GAM curve of height 1 from a
stimulus at time=0 with 13 values of output (time = 0..12
seconds). The 3dcalc command will multiply those 13 values
by the beta weights from sub-brick 3 of your func_slim+orig
dataset.

This gives you a 13 sub-brick response curve for that
particular regressor, where sub-brick zero is always all
zeros (since the GAM curve is 0 at t=0).

Curves for other regressors just need additional 3dcalc
commands, grabbing the correct sub-brick from func_slim:

3dcalc -a wav.1D -b func_slim+orig\[3] -expr 'a*b' -prefix resp_3
3dcalc -a wav.1D -b func_slim+orig\[6] -expr 'a*b' -prefix resp_6
3dcalc -a wav.1D -b func_slim+orig\[9] -expr 'a*b' -prefix resp_9

Only the sub-brick selector and prefix are changing for this.

Just recall that the only thing that 3dDeconvolve gave you
was the height of the curve. The shape is assumed.

- rick